def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main() def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans) main H, W = map(int, input().split()) H map(int, input().split()) map int input().split() ().split () input split W list(input()) for _ in range(H) for _ in range(H) _ range(H) range H for _ in range(H) list(input()) list input() input S = [list(input()) for _ in range(H)] S [list(input()) for _ in range(H)] [-1]*W for _ in range(H) for _ in range(H) _ range(H) range H for _ in range(H) [-1]*W [-1] -1 W left = [[-1]*W for _ in range(H)] left [[-1]*W for _ in range(H)] [-1]*W for _ in range(H) for _ in range(H) _ range(H) range H for _ in range(H) [-1]*W [-1] -1 W right = [[-1]*W for _ in range(H)] right [[-1]*W for _ in range(H)] [-1]*W for _ in range(H) for _ in range(H) _ range(H) range H for _ in range(H) [-1]*W [-1] -1 W up = [[-1]*W for _ in range(H)] up [[-1]*W for _ in range(H)] [-1]*W for _ in range(H) for _ in range(H) _ range(H) range H for _ in range(H) [-1]*W [-1] -1 W down = [[-1]*W for _ in range(H)] down [[-1]*W for _ in range(H)] for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

     i range(H) range H for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

     j range(W) range W if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

     S[i][j] == '.' S[i][j] [i] S i j '.' if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

     j == 0 j 0 left[i][j] = 0 left[i][j] [i] left i j 0 left[i][j] = left[i][j-1] + 1 left[i][j] [i] left i j left[i][j-1] + 1 left[i][j-1] [i] left i j-1 j 1 1 for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

     i range(H) range H for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

     j range(W) range W if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

     S[-1-i][-1-j] == '.' S[-1-i][-1-j] [-1-i] S -1-i -1 i -1-j -1 j '.' if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

     j == 0 j 0 right[-1-i][-1-j] = 0 right[-1-i][-1-j] [-1-i] right -1-i -1 i -1-j -1 j 0 right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1 right[-1-i][-1-j] [-1-i] right -1-i -1 i -1-j -1 j right[-1-i][-1-(j-1)] + 1 right[-1-i][-1-(j-1)] [-1-i] right -1-i -1 i -1-(j-1) -1 j-1 j 1 1 for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

     i range(H) range H for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

     j range(W) range W if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

     S[i][j] == '.' S[i][j] [i] S i j '.' if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

     i == 0 i 0 up[i][j] = 0 up[i][j] [i] up i j 0 up[i][j] = up[i-1][j] + 1 up[i][j] [i] up i j up[i-1][j] + 1 up[i-1][j] [i-1] up i-1 i 1 j 1 for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
     i range(H) range H for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
     j range(W) range W if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
     S[-1-i][-1-j] == '.' S[-1-i][-1-j] [-1-i] S -1-i -1 i -1-j -1 j '.' if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
     i == 0 i 0 down[-1-i][-1-j] = 0 down[-1-i][-1-j] [-1-i] down -1-i -1 i -1-j -1 j 0 down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1 down[-1-i][-1-j] [-1-i] down -1-i -1 i -1-j -1 j down[-1-(i-1)][-1-j] + 1 down[-1-(i-1)][-1-j] [-1-(i-1)] down -1-(i-1) -1 i-1 i 1 -1-j -1 j 1 ans = 0 ans 0 temp = [0] * W temp [0] * W [0] 0 W for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
     i range(H) range H for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
         j range(W) range W temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1 temp[j] temp j left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1 left[i][j] + right[i][j] + down[i][j] + up[i][j] left[i][j] + right[i][j] + down[i][j] left[i][j] + right[i][j] left[i][j] [i] left i j right[i][j] [i] right i j down[i][j] [i] down i j up[i][j] [i] up i j 1 ans = max(ans, max(temp)) ans max(ans, max(temp)) max ans max(temp) max temp print(ans) print ans main() main def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans) def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans) main
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()