import sys
def input(): return sys.stdin.readline().rstrip()
def main():
    h,w=map(int,input().split())
    S=[input() for _ in range(h)]
    L=[[0]*w for _ in range(h)]
    R=[[0]*w for _ in range(h)]
    U=[[0]*w for _ in range(h)]
    D=[[0]*w for _ in range(h)]
    for i in range(h):
        for j in range(w):
            if S[i][j]=='#':
                L[i][j]=0
                U[i][j]=0
                continue
            if i==0:U[i][j]=1
            else:U[i][j]=U[i-1][j]+1
            if j==0:L[i][j]=1
            else:L[i][j]=L[i][j-1]+1
    for i in range(h-1,-1,-1):
        for j in range(w-1,-1,-1):
            if S[i][j]=='#':
                R[i][j]=0
                D[i][j]=0
                continue
            if i==h-1:D[i][j]=1
            else:D[i][j]=D[i+1][j]+1
            if j==w-1:R[i][j]=1
            else:R[i][j]=R[i][j+1]+1 
    X=[[l+r+u+d-3 for l,r,u,d in zip(ll,rr,uu,dd)] for ll,rr,uu,dd in zip(L,R,U,D)]
    print(max([max(x) for x in X]))


if __name__=='__main__':
    main() import sys sys def input(): return sys.stdin.readline().rstrip() input def main():
    h,w=map(int,input().split())
    S=[input() for _ in range(h)]
    L=[[0]*w for _ in range(h)]
    R=[[0]*w for _ in range(h)]
    U=[[0]*w for _ in range(h)]
    D=[[0]*w for _ in range(h)]
    for i in range(h):
        for j in range(w):
            if S[i][j]=='#':
                L[i][j]=0
                U[i][j]=0
                continue
            if i==0:U[i][j]=1
            else:U[i][j]=U[i-1][j]+1
            if j==0:L[i][j]=1
            else:L[i][j]=L[i][j-1]+1
    for i in range(h-1,-1,-1):
        for j in range(w-1,-1,-1):
            if S[i][j]=='#':
                R[i][j]=0
                D[i][j]=0
                continue
            if i==h-1:D[i][j]=1
            else:D[i][j]=D[i+1][j]+1
            if j==w-1:R[i][j]=1
            else:R[i][j]=R[i][j+1]+1 
    X=[[l+r+u+d-3 for l,r,u,d in zip(ll,rr,uu,dd)] for ll,rr,uu,dd in zip(L,R,U,D)]
    print(max([max(x) for x in X])) main h,w=map(int,input().split()) h map(int,input().split()) map int input().split() ().split () input split w input() for _ in range(h) for _ in range(h) _ range(h) range h for _ in range(h) input() input S=[input() for _ in range(h)] S [input() 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 L=[[0]*w for _ in range(h)] L [[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 R=[[0]*w for _ in range(h)] R [[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 U=[[0]*w for _ in range(h)] U [[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 D=[[0]*w for _ in range(h)] D [[0]*w for _ in range(h)] for i in range(h):
        for j in range(w):
            if S[i][j]=='#':
                L[i][j]=0
                U[i][j]=0
                continue
            if i==0:U[i][j]=1
            else:U[i][j]=U[i-1][j]+1
            if j==0:L[i][j]=1
            else:L[i][j]=L[i][j-1]+1
     i range(h) range h for j in range(w):
            if S[i][j]=='#':
                L[i][j]=0
                U[i][j]=0
                continue
            if i==0:U[i][j]=1
            else:U[i][j]=U[i-1][j]+1
            if j==0:L[i][j]=1
            else:L[i][j]=L[i][j-1]+1
     j range(w) range w if S[i][j]=='#':
                L[i][j]=0
                U[i][j]=0
                continue
             S[i][j]=='#' S[i][j] [i] S i j '#' L[i][j]=0 L[i][j] [i] L i j 0 U[i][j]=0 U[i][j] [i] U i j 0 continue if i==0:U[i][j]=1
            else:U[i][j]=U[i-1][j]+1
             i==0 i 0 if j==0:L[i][j]=1
            else:L[i][j]=L[i][j-1]+1
     j==0 j 0 for i in range(h-1,-1,-1):
        for j in range(w-1,-1,-1):
            if S[i][j]=='#':
                R[i][j]=0
                D[i][j]=0
                continue
            if i==h-1:D[i][j]=1
            else:D[i][j]=D[i+1][j]+1
            if j==w-1:R[i][j]=1
            else:R[i][j]=R[i][j+1]+1 
     i range(h-1,-1,-1) range h-1 h 1 -1 -1 for j in range(w-1,-1,-1):
            if S[i][j]=='#':
                R[i][j]=0
                D[i][j]=0
                continue
            if i==h-1:D[i][j]=1
            else:D[i][j]=D[i+1][j]+1
            if j==w-1:R[i][j]=1
            else:R[i][j]=R[i][j+1]+1 
     j range(w-1,-1,-1) range w-1 w 1 -1 -1 if S[i][j]=='#':
                R[i][j]=0
                D[i][j]=0
                continue
             S[i][j]=='#' S[i][j] [i] S i j '#' R[i][j]=0 R[i][j] [i] R i j 0 D[i][j]=0 D[i][j] [i] D i j 0 continue if i==h-1:D[i][j]=1
            else:D[i][j]=D[i+1][j]+1
             i==h-1 i h-1 h 1 if j==w-1:R[i][j]=1
            else:R[i][j]=R[i][j+1]+1 
     j==w-1 j w-1 w 1 [l+r+u+d-3 for l,r,u,d in zip(ll,rr,uu,dd)] for ll,rr,uu,dd in zip(L,R,U,D) for ll,rr,uu,dd in zip(L,R,U,D) ll rr uu dd zip(L,R,U,D) zip L R U D for ll,rr,uu,dd in zip(L,R,U,D) [l+r+u+d-3 for l,r,u,d in zip(ll,rr,uu,dd)] X=[[l+r+u+d-3 for l,r,u,d in zip(ll,rr,uu,dd)] for ll,rr,uu,dd in zip(L,R,U,D)] X [[l+r+u+d-3 for l,r,u,d in zip(ll,rr,uu,dd)] for ll,rr,uu,dd in zip(L,R,U,D)] max(x) for x in X for x in X x X for x in X max(x) max x print(max([max(x) for x in X])) print max([max(x) for x in X]) max [max(x) for x in X] if __name__=='__main__':
    main() __name__=='__main__' __name__ '__main__' main() main def main():
    h,w=map(int,input().split())
    S=[input() for _ in range(h)]
    L=[[0]*w for _ in range(h)]
    R=[[0]*w for _ in range(h)]
    U=[[0]*w for _ in range(h)]
    D=[[0]*w for _ in range(h)]
    for i in range(h):
        for j in range(w):
            if S[i][j]=='#':
                L[i][j]=0
                U[i][j]=0
                continue
            if i==0:U[i][j]=1
            else:U[i][j]=U[i-1][j]+1
            if j==0:L[i][j]=1
            else:L[i][j]=L[i][j-1]+1
    for i in range(h-1,-1,-1):
        for j in range(w-1,-1,-1):
            if S[i][j]=='#':
                R[i][j]=0
                D[i][j]=0
                continue
            if i==h-1:D[i][j]=1
            else:D[i][j]=D[i+1][j]+1
            if j==w-1:R[i][j]=1
            else:R[i][j]=R[i][j+1]+1 
    X=[[l+r+u+d-3 for l,r,u,d in zip(ll,rr,uu,dd)] for ll,rr,uu,dd in zip(L,R,U,D)]
    print(max([max(x) for x in X])) def main():
    h,w=map(int,input().split())
    S=[input() for _ in range(h)]
    L=[[0]*w for _ in range(h)]
    R=[[0]*w for _ in range(h)]
    U=[[0]*w for _ in range(h)]
    D=[[0]*w for _ in range(h)]
    for i in range(h):
        for j in range(w):
            if S[i][j]=='#':
                L[i][j]=0
                U[i][j]=0
                continue
            if i==0:U[i][j]=1
            else:U[i][j]=U[i-1][j]+1
            if j==0:L[i][j]=1
            else:L[i][j]=L[i][j-1]+1
    for i in range(h-1,-1,-1):
        for j in range(w-1,-1,-1):
            if S[i][j]=='#':
                R[i][j]=0
                D[i][j]=0
                continue
            if i==h-1:D[i][j]=1
            else:D[i][j]=D[i+1][j]+1
            if j==w-1:R[i][j]=1
            else:R[i][j]=R[i][j+1]+1 
    X=[[l+r+u+d-3 for l,r,u,d in zip(ll,rr,uu,dd)] for ll,rr,uu,dd in zip(L,R,U,D)]
    print(max([max(x) for x in X])) main def input(): return sys.stdin.readline().rstrip() def input(): return sys.stdin.readline().rstrip() input
import sys
def input(): return sys.stdin.readline().rstrip()
def main():
    h,w=map(int,input().split())
    S=[input() for _ in range(h)]
    L=[[0]*w for _ in range(h)]
    R=[[0]*w for _ in range(h)]
    U=[[0]*w for _ in range(h)]
    D=[[0]*w for _ in range(h)]
    for i in range(h):
        for j in range(w):
            if S[i][j]=='#':
                L[i][j]=0
                U[i][j]=0
                continue
            if i==0:U[i][j]=1
            else:U[i][j]=U[i-1][j]+1
            if j==0:L[i][j]=1
            else:L[i][j]=L[i][j-1]+1
    for i in range(h-1,-1,-1):
        for j in range(w-1,-1,-1):
            if S[i][j]=='#':
                R[i][j]=0
                D[i][j]=0
                continue
            if i==h-1:D[i][j]=1
            else:D[i][j]=D[i+1][j]+1
            if j==w-1:R[i][j]=1
            else:R[i][j]=R[i][j+1]+1 
    X=[[l+r+u+d-3 for l,r,u,d in zip(ll,rr,uu,dd)] for ll,rr,uu,dd in zip(L,R,U,D)]
    print(max([max(x) for x in X]))


if __name__=='__main__':
    main()