def main():
    import sys
    input = sys.stdin.read().split()
    idx = 0
    H = int(input[idx])
    idx += 1
    W = int(input[idx])
    idx +=1
    grid = []
    for _ in range(H):
        grid.append(input[idx])
        idx +=1
    
    left = [[0]*W for _ in range(H)]
    right = [[0]*W for _ in range(H)]
    up = [[0]*W for _ in range(H)]
    down = [[0]*W for _ in range(H)]
    
    # Compute left and right
    for i in range(H):
        for j in range(W):
            if grid[i][j] == '#':
                if j == 0:
                    left[i][j] = 1
                else:
                    left[i][j] = left[i][j-1] + 1
            else:
                left[i][j] = 0
        for j in range(W-1, -1, -1):
            if grid[i][j] == '#':
                if j == W-1:
                    right[i][j] = 1
                else:
                    right[i][j] = right[i][j+1] + 1
            else:
                right[i][j] = 0
    
    # Compute up and down
    for j in range(W):
        for i in range(H):
            if grid[i][j] == '#':
                if i == 0:
                    up[i][j] = 1
                else:
                    up[i][j] = up[i-1][j] + 1
            else:
                up[i][j] = 0
        for i in range(H-1, -1, -1):
            if grid[i][j] == '#':
                if i == H-1:
                    down[i][j] = 1
                else:
                    down[i][j] = down[i+1][j] + 1
            else:
                down[i][j] = 0
    
    min_s = float('inf')
    found_black = False
    for i in range(H):
        for j in range(W):
            if grid[i][j] == '#':
                found_black = True
                horizontal = left[i][j] + right[i][j] -1
                vertical = up[i][j] + down[i][j] -1
                s_ij = min(horizontal, vertical)
                if s_ij < min_s:
                    min_s = s_ij
    
    print(min_s if found_black else 0)

if __name__ == '__main__':
    main()