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

class Program
{
    static void Main(string[] args)
    {
        new Program().Calc();
    }

    Scanner cin;

    public Program() { }

    bool chmax<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) < 0) { a = b; return true; } return false; }
    bool chmin<T>(ref T a, T b) where T : IComparable<T> { if (b.CompareTo(a) < 0) { a = b; return true; } return false; }

    void Calc()
    {
        cin = new Scanner();
        int H = cin.nextInt();
        int W = cin.nextInt();

        char[][] map = new char[H][];

        for (int i = 0; i < H; ++i)
        {
            map[i] = cin.next().ToCharArray();
        }

        int[,] mapU = new int[H, W];

        for (int y = 1; y < H; ++y)
        {
            for (int x = 0; x < W; ++x)
            {
                if (map[y][x] != '#' && map[y - 1][x] == '.')
                {
                    mapU[y, x] = mapU[y - 1, x] + 1;
                }
            }
        }

        int[,] mapD = new int[H, W];

        for (int y = H - 2; y >= 0; --y)
        {
            for (int x = 0; x < W; ++x)
            {
                if (map[y][x] != '#' && map[y + 1][x] == '.')
                {
                    mapD[y, x] = mapD[y + 1, x] + 1;
                }
            }
        }

        int[,] mapL = new int[H, W];

        for (int y = 0; y < H; ++y)
        {
            for (int x = 1; x < W; ++x)
            {
                if (map[y][x] != '#' && map[y][x-1] == '.')
                {
                    mapL[y, x] = mapL[y, x-1] + 1;
                }
            }
        }

        int[,] mapR = new int[H, W];

        for (int y = 0; y < H; ++y)
        {
            for (int x = W - 2; x >= 0; --x)
            {
                if (map[y][x] != '#' && map[y][x+1] == '.')
                {
                    mapR[y, x] = mapR[y, x+1] + 1;
                }
            }
        }

        int maxCount = 0;
        int maxY = 0;
        int maxX = 0;

        for (int y = 0; y < H; ++y)
        {
            for (int x = 0; x < W; ++x)
            {
                int count = mapU[y, x] + mapD[y, x] + mapL[y, x] + mapR[y, x] + 1;
                if (maxCount < count)
                {
                    maxCount = count;
                    maxY = y;
                    maxX = x;
                }
            }
        }

        WriteLine(maxCount);
    }
}

public static class StringExtension
{
    public static char GetChar1(this string str, int indexOneBase)
    {
        return str[indexOneBase - 1];
    }
}

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: 93320