using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;



class Myon
{
    public Myon() { }
    public static int Main()
    {
        cin = new Scanner();
        new Myon().calc();
        return 0;
    }

    static Scanner cin;

    void calc()
    {
        var H = cin.nextInt();
        var W = cin.nextInt();
        string[] S = new string[H+2];
        var line = "";
        var tu = new string('#', W+2);
        S[0] = tu;
        S[H + 1] = tu;
        for(var i = 0;i < H; i++)
        {
            line = "#" + cin.next() + "#";
            S[i+1] = line;
        }
        int[,] L = calcArrayLO(W, H, -1, 0, S);
        int[,] R = calcArrayRU(W, H, 1, 0, S);
        int[,] U = calcArrayRU(W, H, 0, 1, S);
        int[,] O = calcArrayLO(W, H, 0, -1, S);

        var ret = 0;
        char c;
        var tmp = 0;
        for (var w = 1; w < W + 1; w++)
        {
            for(var h = 1; h < H + 1; h++)
            {
                c = S[h][w];
                if(c == '.')
                {
                    tmp = L[h - 1, w - 1] + R[h - 1, w - 1] + U[h - 1, w - 1] + O[h - 1, w - 1] - 3;
                    ret = Math.Max(ret, tmp);
                }
            }
        }

        Console.WriteLine(ret);
    }


    int[,] calcArrayLO(int w, int h, int wdiff, int hdiff, string[] S)
    {
        int[,] ret = new int[h, w];
        var c = '0';
        for(var i = 0;i < w; i++)
        {
            for(var j = 0;j < h; j++)
            {
                c = S[j + hdiff + 1][i + wdiff + 1];
                if(c == '#')
                {
                    ret[j, i] = 1;
                }
                else
                {
                    ret[j, i] = ret[j + hdiff, i + wdiff] + 1;
                }
                    
            }
        }

        return ret;
    }

    int[,] calcArrayRU(int w, int h, int wdiff, int hdiff, string[] S)
    {
        int[,] ret = new int[h, w];
        var c = '0';
        for (var i = w-1; 0 <= i; i--)
        {
            for (var j = h-1;0 <= j; j--)
            {
                c = S[j + hdiff + 1][i + wdiff + 1];
                if (c == '#')
                {
                    ret[j, i] = 1;
                }
                else
                {
                    ret[j, i] = ret[j + hdiff, i + wdiff] + 1;
                }

            }
        }

        return ret;
    }
}



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 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: 91144