### BUGGY CODE ###

import sys
sys.setrecursionlimit(10**9)
def input():
    return sys.stdin.readline().rstrip()

def main():
    H,W=map(int,input().split())
    S=[list(input()) for i in range(H)]
    ans=0
    memo_y = [[-float('inf')]*W for i in range(H)]
    memo_x = [[-float('inf')]*W for i in range(H)]
    for y in range(H):
        for x in range(W):
            c = 0
            if S[y][x]=='.':
                c += 1
                c_x = 0
                c_y = 0
                tmp_x = [x]
                tmp_y = [y]
                if memo_x[y][x] == -float('inf'):
                    for i in range(1, x+1):
                        if S[y][x-i] == '.':
                            c_x += 1
                            tmp_x.append(i)
                        else:
                            break
                    for i in range(x+1, W):
                        if S[y][i] == '.':
                            c_x += 1
                            tmp_x.append(i)
                        else:
                            break
                    for i in tmp_x:
                        memo_x[y][i] = c_x
                else:
                    c_x += memo_x[y][x]
                if memo_y[y][x] == -float('inf'):
                    for i in range(1, y+1):
                        if S[y-i][x] == '.':
                            c_y += 1
                            tmp_y.append(i)
                        else:
                            break
                    for i in range(y+1, H):
                        if S[i][x] == '.':
                            c_y += 1
                            tmp_y.append(i)
                        else:
                            break
                    for i in tmp_y:
                        memo_y[i][x] = c_y
                else:
                    c_y += memo_y[y][x]
                c += c_x + c_y
            ans=max(ans,c)
    print(ans)
                

if __name__ == '__main__':
    main()


### FIXED CODE ###

import sys
sys.setrecursionlimit(10**9)


def input():
    return sys.stdin.readline().rstrip()


def main():
    H, W = map(int, input().split())
    S = [list(input()) for i in range(H)]
    ans = 0
    memo_y = [[-1]*W for i in range(H)]
    memo_x = [[-1]*W for i in range(H)]
    for y in range(H):
        for x in range(W):
            c = 0
            if S[y][x] == '.':
                c += 1
                c_x = 0
                c_y = 0
                tmp_x = [x]
                tmp_y = [y]
                if memo_x[y][x] == -1:
                    for i in range(1, x+1):
                        if S[y][x-i] == '.':
                            c_x += 1
                            tmp_x.append(i)
                        else:
                            break
                    for i in range(x+1, W):
                        if S[y][i] == '.':
                            c_x += 1
                            tmp_x.append(i)
                        else:
                            break
                    for i in tmp_x:
                        memo_x[y][i] = c_x
                else:
                    c_x += memo_x[y][x]
                if memo_y[y][x] == -1:
                    for i in range(1, y+1):
                        if S[y-i][x] == '.':
                            c_y += 1
                            tmp_y.append(i)
                        else:
                            break
                    for i in range(y+1, H):
                        if S[i][x] == '.':
                            c_y += 1
                            tmp_y.append(i)
                        else:
                            break
                    for i in tmp_y:
                        memo_y[i][x] = c_y
                else:
                    c_y += memo_y[y][x]
                c += c_x + c_y
            ans = max(ans, c)
    print(ans)


if __name__ == '__main__':
    main()