#include <iostream>
#include <cstdio>
#define N 2005
using namespace std;

int n,m, mx, c, s[N][N];
char a[N][N];
int main()
{
	int i, j;
	cin >> n >> m;
	for (i = 1; i <= n; i++) {
		scanf ("%s", &a[i][1]);
	}
	for (i = 1; i<= n; i++) {
		c = 0;
		for (j = 1; j <= m; j++) {
			if (a[i][j] == '#') c = 0;
			else {
				c++;
				s[i][j] += c;
			}
		}
		c = 0;
		for (j = m; j >= 1; j--) {
			if (a[i][j] == '#') c = 0;
			else {
				c++;
				s[i][j] += c;
			}
		}
	}
	for (j = 1; j <= m; j++) {
		c = 0;
		for (i = 1; i <= n; i++) {
			if (a[i][j] == '#') c = 0;
			else {
				c++;
				s[i][j] += c;
			}
		}
		c = 0;
		for (i = n; i >= 1; i--) {
			if (a[i][j] == '#') c = 0;
			else {
				c++;
				s[i][j] += c;
			}
		}
	}
	for (i =1; i <= n; i++) {
		for (j = 1; j <= m; j++) {
			if (a[i][j] != '#') mx = max(mx, s[i][j] - 3);
		}
	}
	cout << mx;
    return 0;
}
