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

class Program
{
    static void Main(string[] args)
    {
        var sc = new Scanner();

        var h = sc.nextInt();
        var w = sc.nextInt();
        var s = new string[h];

        for (int i = 0; i < h; i++)
        {
            s[i] = sc.next();
        }

        var memol = new int[h, w];
        var memou = new int[h, w];
        var memor = new int[h, w];
        var memod = new int[h, w];
        for (int i = 0; i < s[0].Length; i++)
        {
            for (int j = 0; j < s.Length; j++)
            {
                if (s[j][i] == '.')
                {
                    // 左から
                    if (i == 0) memol[j, i] = 1;
                    else memol[j, i] = memol[j, i - 1] + 1;

                    // 上から
                    if (j == 0) memou[j, i] = 1;
                    else memou[j, i] = memou[j - 1, i] + 1;
                }
            }
        }
        for (int i = s[0].Length - 1; 0 <= i; i--)
        {
            for (int j = s.Length - 1; 0 <= j; j--)
            {
                if (s[j][i] == '.')
                {
                    // 右から
                    if (i == s[0].Length - 1) memor[j, i] = 1;
                    else memor[j, i] = memor[j, i + 1] + 1;

                    // 下から
                    if (j == s.Length - 1) memod[j, i] = 1;
                    else memod[j, i] = memod[j + 1, i] + 1;
                }
            }
        }

        int ans = 0;

        for (int y = 0; y < h; y++)
        {
            for (int x = 0; x < w; x++)
            {
                if (s[y][x] == '.') ans = Math.Max(ans, memol[y, x] + memou[y, x] + memor[y, x] + memod[y, x] - 3);
            }
        }

        Console.WriteLine(ans);
    }
}

// chokudai's Scanner
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: 93208