using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        var input = Console.ReadLine().Split(' ');

        var height = int.Parse(input[0]);
        var width = int.Parse(input[1]);
        var maze = new bool[height, width];
        for(var i = 0; i < height; i++)
        {
            var line = Console.ReadLine().ToCharArray();
            for (var j = 0; j < width; j++)
            {
                if(line[j] == '.')
                {
                    maze[i, j] = true;
                }
                else
                {
                    maze[i, j] = false;
                }
            }
        }

        var left = new int[height, width];

        for (var i = 0; i < height; i++)
        {
            for (var j = 0; j < width; j++)
            {
                if (j == 0)
                {
                    if (maze[i, j] == true) 
                    {
                        left[i, j] = 1;
                    }
                    else
                    {
                        left[i, j] = 0;
                    }
                }
                else
                {
                    if (maze[i, j] == true)
                    {
                        left[i, j] = left[i, j - 1] + 1;
                    }
                    else
                    {
                        left[i, j] = 0;
                    }
                }
            }
        }

        var under = new int[height, width];
        for (var i = height - 1; i > -1 ; i--)
        {
            for (var j = 0; j < width; j++)
            {
                if (i == height - 1)
                {
                    if (maze[i, j] == true)
                    {
                        under[i, j] = 1;
                    }
                    else
                    {
                        under[i, j] = 0;
                    }
                }
                else
                {
                    if (maze[i, j] == true)
                    {
                        under[i, j] = under[i + 1, j] + 1;
                    }
                    else
                    {
                        under[i, j] = 0;
                    }
                }
            }
        }

        var right = new int[height, width];
        for (var i = 0; i < height; i++)
        {
            for (var j = width - 1; j > -1; j--)
            {
                if (j == width - 1)
                {
                    if (maze[i, j] == true)
                    {
                        right[i, j] = 1;
                    }
                    else
                    {
                        right[i, j] = 0;
                    }
                }
                else
                {
                    if (maze[i, j] == true)
                    {
                        right[i, j] = right[i, j + 1] + 1;
                    }
                    else
                    {
                        right[i, j] = 0;
                    }
                }
            }
        }

        var up = new int[height, width];

        for (var i = 0; i < height; i++)
        {
            for (var j = 0; j < width; j++)
            {
                if (i == 0)
                {
                    if (maze[i, j] == true)
                    {
                        up[i, j] = 1;
                    }
                    else
                    {
                        up[i, j] = 0;
                    }
                }
                else
                {
                    if (maze[i, j] == true)
                    {
                        up[i, j] = up[i - 1, j] + 1;
                    }
                    else
                    {
                        up[i, j] = 0;
                    }
                }
            }
        }

        var ans = 0;
        for (var i = 0; i < height; i++)
        {
            for (var j = 0; j < width; j++)
            {
                var n = 0;
                n = left[i, j] + right[i, j] + up[i, j] + under[i, j];
                if(n > ans)
                {
                    ans = n;
                }
            }
        }

        Console.WriteLine(ans - 3);

    }
}


Measured memory_bytes: 81464