using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

class Program
{
    const int MOD = 1000000007;
    int height;
    int width;
    static void Main(string[] args)
    {
        new Program().Solve();
    }

    void Solve()
    {
        Scanner cin = new Scanner();
        int h = cin.NextInt();
        int w = cin.NextInt();
        height = h;
        width = w;
        string[] board = new string[h];
        for (int i = 0; i < h; i++)
        {
            board[i] = cin.Next();
        }

        long[,] l = new long[h, w];
        long[,] r = new long[h, w];
        long[,] u = new long[h, w];
        long[,] b = new long[h, w];


        for (int i = 0; i < h; i++)
        {
            int curCount = 0;
            for (int j = 0; j < w; j++)
            {
                if (board[i][j] == '#')
                {
                    curCount = 0;
                    l[i, j] = curCount;
                }
                else
                {
                    l[i, j] = curCount;
                    curCount++;
                }

            }
        }

        for (int i = 0; i < h; i++)
        {
            int curCount = 0;
            for (int j = w-1; j >= 0; j--)
            {
                if (board[i][j] == '#')
                {
                    curCount = 0;
                    r[i, j] = curCount;
                }
                else
                {
                    r[i, j] = curCount;
                    curCount++;
                }
            }
        }

        for (int j = 0; j < w; j++)
        {
            int curCount = 0;
            for (int i = 0; i < h; i++)
            {
                if (board[i][j] == '#')
                {
                    curCount = 0;
                    u[i, j] = curCount;
                }
                else
                {
                    u[i, j] = curCount;
                    curCount++;
                }

            }
        }

        for (int j = 0; j < w; j++)
        {
            int curCount = 0;
            for (int i = h - 1; i >= 0; i--)
            {
                if (board[i][j] == '#')
                {
                    curCount = 0;
                    b[i, j] = curCount;
                }
                else
                {
                    b[i, j] = curCount;
                    curCount++;
                }
            }
        }

        long max = 0;
        for (int ri = 0; ri < h; ri++)
        {
            for (int ci = 0; ci < w; ci++)
            {
                long count = 0;
                if (board[ri][ci] == '#')
                {
                    continue;
                }
                count = l[ri, ci] + r[ri, ci] + u[ri, ci] + b[ri, ci];
                max = Math.Max(max, count);
            }
        }
        Console.WriteLine(max + 1);
    }
    bool IsInside(int row, int column)
    {
        if (0 <= row && row < height && 0 <= column && column < width)
        {
            return true;
        }
        return false;
    }

}


class Scanner
{
    string[] s;
    int i;

    char[] cs = new char[] { ' ' };

    public Scanner()
    {
        s = new string[0];
        i = 0;
    }

    public string Next()
    {
        if (i < s.Length) return s[i++];
        string st = Console.ReadLine();
        while (st == "") st = Console.ReadLine();
        s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
        if (s.Length == 0) return Next();
        i = 0;
        return s[i++];
    }

    public int NextInt()
    {
        return int.Parse(Next());
    }

    public char[] ArrayChar()
    {
        return Next().ToCharArray();
    }
    public int[] ArrayInt(int N, int add = 0)
    {
        int[] Array = new int[N];
        for (int i = 0; i < N; i++)
        {
            Array[i] = NextInt() + add;
        }
        return Array;
    }

    public long NextLong()
    {
        return long.Parse(Next());
    }

    public long[] ArrayLong(int N, long add = 0)
    {
        long[] Array = new long[N];
        for (int i = 0; i < N; i++)
        {
            Array[i] = NextLong() + add;
        }
        return Array;
    }

    public double NextDouble()
    {
        return double.Parse(Next());
    }


    public double[] ArrayDouble(int N, double add = 0)
    {
        double[] Array = new double[N];
        for (int i = 0; i < N; i++)
        {
            Array[i] = NextDouble() + add;
        }
        return Array;
    }
}


Measured memory_bytes: 151576