def main():
    H, W = map(int, input().split())
    A = [list(input()) for i in range(H)]
    right = [[0] * W for _ in range(H)]
    left = [[0] * W for _ in range(H)]
    upper = [[0] * W for _ in range(H)]
    under = [[0] * W for _ in range(H)]

    num_max_loc = 0

    for i in range(H):
        tmp_num = 0
        for j in range(W):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                left[i][j] = tmp_num

    for i in range(H):
        tmp_num = 0
        for j in range(W-1, -1, -1):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                right[i][j] = tmp_num

    for i in range(W):
        tmp_num = 0
        for j in range(H):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                upper[j][i] = tmp_num

    for i in range(W):
        tmp_num = 0
        for j in range(H-1, -1, -1):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                under[j][i] = tmp_num

    for i in range(H):
        for j in range(W):
            tmp_sum = (
                left[i][j] + right[i][j] + upper[i][j] + under[i][j] - 3)
            num_max_loc = max(num_max_loc, tmp_sum)

    print(num_max_loc)


if __name__ == '__main__':
    main() def main():
    H, W = map(int, input().split())
    A = [list(input()) for i in range(H)]
    right = [[0] * W for _ in range(H)]
    left = [[0] * W for _ in range(H)]
    upper = [[0] * W for _ in range(H)]
    under = [[0] * W for _ in range(H)]

    num_max_loc = 0

    for i in range(H):
        tmp_num = 0
        for j in range(W):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                left[i][j] = tmp_num

    for i in range(H):
        tmp_num = 0
        for j in range(W-1, -1, -1):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                right[i][j] = tmp_num

    for i in range(W):
        tmp_num = 0
        for j in range(H):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                upper[j][i] = tmp_num

    for i in range(W):
        tmp_num = 0
        for j in range(H-1, -1, -1):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                under[j][i] = tmp_num

    for i in range(H):
        for j in range(W):
            tmp_sum = (
                left[i][j] + right[i][j] + upper[i][j] + under[i][j] - 3)
            num_max_loc = max(num_max_loc, tmp_sum)

    print(num_max_loc) main H, W = map(int, input().split()) H map(int, input().split()) map int input().split() ().split () input split W list(input()) for i in range(H) for i in range(H) i range(H) range H for i in range(H) list(input()) list input() input A = [list(input()) for i in range(H)] A [list(input()) for i in range(H)] [0] * W for _ in range(H) for _ in range(H) _ range(H) range H for _ in range(H) [0] * W [0] 0 W right = [[0] * W for _ in range(H)] right [[0] * W for _ in range(H)] [0] * W for _ in range(H) for _ in range(H) _ range(H) range H for _ in range(H) [0] * W [0] 0 W left = [[0] * W for _ in range(H)] left [[0] * W for _ in range(H)] [0] * W for _ in range(H) for _ in range(H) _ range(H) range H for _ in range(H) [0] * W [0] 0 W upper = [[0] * W for _ in range(H)] upper [[0] * W for _ in range(H)] [0] * W for _ in range(H) for _ in range(H) _ range(H) range H for _ in range(H) [0] * W [0] 0 W under = [[0] * W for _ in range(H)] under [[0] * W for _ in range(H)] num_max_loc = 0 num_max_loc 0 for i in range(H):
        tmp_num = 0
        for j in range(W):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                left[i][j] = tmp_num

     i range(H) range H tmp_num = 0 tmp_num 0 for j in range(W):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                left[i][j] = tmp_num

     j range(W) range W if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                left[i][j] = tmp_num

     A[i][j] == "#" A[i][j] [i] A i j "#" tmp_num = 0 tmp_num 0 tmp_num += 1 tmp_num 1 left[i][j] = tmp_num left[i][j] [i] left i j tmp_num for i in range(H):
        tmp_num = 0
        for j in range(W-1, -1, -1):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                right[i][j] = tmp_num

     i range(H) range H tmp_num = 0 tmp_num 0 for j in range(W-1, -1, -1):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                right[i][j] = tmp_num

     j range(W-1, -1, -1) range W-1 W 1 -1 -1 if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                right[i][j] = tmp_num

     A[i][j] == "#" A[i][j] [i] A i j "#" tmp_num = 0 tmp_num 0 tmp_num += 1 tmp_num 1 right[i][j] = tmp_num right[i][j] [i] right i j tmp_num for i in range(W):
        tmp_num = 0
        for j in range(H):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                upper[j][i] = tmp_num

     i range(W) range W tmp_num = 0 tmp_num 0 for j in range(H):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                upper[j][i] = tmp_num

     j range(H) range H if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                upper[j][i] = tmp_num

     A[j][i] == "#" A[j][i] [j] A j i "#" tmp_num = 0 tmp_num 0 tmp_num += 1 tmp_num 1 upper[j][i] = tmp_num upper[j][i] [j] upper j i tmp_num for i in range(W):
        tmp_num = 0
        for j in range(H-1, -1, -1):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                under[j][i] = tmp_num

     i range(W) range W tmp_num = 0 tmp_num 0 for j in range(H-1, -1, -1):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                under[j][i] = tmp_num

     j range(H-1, -1, -1) range H-1 H 1 -1 -1 if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                under[j][i] = tmp_num

     A[j][i] == "#" A[j][i] [j] A j i "#" tmp_num = 0 tmp_num 0 tmp_num += 1 tmp_num 1 under[j][i] = tmp_num under[j][i] [j] under j i tmp_num for i in range(H):
        for j in range(W):
            tmp_sum = (
                left[i][j] + right[i][j] + upper[i][j] + under[i][j] - 3)
            num_max_loc = max(num_max_loc, tmp_sum)

     i range(H) range H for j in range(W):
            tmp_sum = (
                left[i][j] + right[i][j] + upper[i][j] + under[i][j] - 3)
            num_max_loc = max(num_max_loc, tmp_sum)

     j range(W) range W tmp_sum = (
                left[i][j] + right[i][j] + upper[i][j] + under[i][j] - 3) tmp_sum left[i][j] + right[i][j] + upper[i][j] + under[i][j] - 3 left[i][j] + right[i][j] + upper[i][j] + under[i][j] left[i][j] + right[i][j] + upper[i][j] left[i][j] + right[i][j] left[i][j] [i] left i j right[i][j] [i] right i j upper[i][j] [i] upper i j under[i][j] [i] under i j 3 num_max_loc = max(num_max_loc, tmp_sum) num_max_loc max(num_max_loc, tmp_sum) max num_max_loc tmp_sum print(num_max_loc) print num_max_loc if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main def main():
    H, W = map(int, input().split())
    A = [list(input()) for i in range(H)]
    right = [[0] * W for _ in range(H)]
    left = [[0] * W for _ in range(H)]
    upper = [[0] * W for _ in range(H)]
    under = [[0] * W for _ in range(H)]

    num_max_loc = 0

    for i in range(H):
        tmp_num = 0
        for j in range(W):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                left[i][j] = tmp_num

    for i in range(H):
        tmp_num = 0
        for j in range(W-1, -1, -1):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                right[i][j] = tmp_num

    for i in range(W):
        tmp_num = 0
        for j in range(H):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                upper[j][i] = tmp_num

    for i in range(W):
        tmp_num = 0
        for j in range(H-1, -1, -1):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                under[j][i] = tmp_num

    for i in range(H):
        for j in range(W):
            tmp_sum = (
                left[i][j] + right[i][j] + upper[i][j] + under[i][j] - 3)
            num_max_loc = max(num_max_loc, tmp_sum)

    print(num_max_loc) def main():
    H, W = map(int, input().split())
    A = [list(input()) for i in range(H)]
    right = [[0] * W for _ in range(H)]
    left = [[0] * W for _ in range(H)]
    upper = [[0] * W for _ in range(H)]
    under = [[0] * W for _ in range(H)]

    num_max_loc = 0

    for i in range(H):
        tmp_num = 0
        for j in range(W):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                left[i][j] = tmp_num

    for i in range(H):
        tmp_num = 0
        for j in range(W-1, -1, -1):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                right[i][j] = tmp_num

    for i in range(W):
        tmp_num = 0
        for j in range(H):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                upper[j][i] = tmp_num

    for i in range(W):
        tmp_num = 0
        for j in range(H-1, -1, -1):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                under[j][i] = tmp_num

    for i in range(H):
        for j in range(W):
            tmp_sum = (
                left[i][j] + right[i][j] + upper[i][j] + under[i][j] - 3)
            num_max_loc = max(num_max_loc, tmp_sum)

    print(num_max_loc) main
def main():
    H, W = map(int, input().split())
    A = [list(input()) for i in range(H)]
    right = [[0] * W for _ in range(H)]
    left = [[0] * W for _ in range(H)]
    upper = [[0] * W for _ in range(H)]
    under = [[0] * W for _ in range(H)]

    num_max_loc = 0

    for i in range(H):
        tmp_num = 0
        for j in range(W):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                left[i][j] = tmp_num

    for i in range(H):
        tmp_num = 0
        for j in range(W-1, -1, -1):
            if A[i][j] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                right[i][j] = tmp_num

    for i in range(W):
        tmp_num = 0
        for j in range(H):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                upper[j][i] = tmp_num

    for i in range(W):
        tmp_num = 0
        for j in range(H-1, -1, -1):
            if A[j][i] == "#":
                tmp_num = 0
            else:
                tmp_num += 1
                under[j][i] = tmp_num

    for i in range(H):
        for j in range(W):
            tmp_sum = (
                left[i][j] + right[i][j] + upper[i][j] + under[i][j] - 3)
            num_max_loc = max(num_max_loc, tmp_sum)

    print(num_max_loc)


if __name__ == '__main__':
    main()
