#include <algorithm>
#include <iostream>
using namespace std;

const int MAXN = 2005;
int val[MAXN][MAXN];
char mp[MAXN][MAXN];
int n, m;

int main() {
	cin >> n >> m;
	for (int i = 0; i < n; i++)
		for (int j = 0; j < m; j++)
			cin >> mp[i][j];
	for (int i = 0; i < n; i++) {
		int ls = -1;
		for (int j = 0; j < m; j++) {
			if (mp[i][j] == '#')
				ls = j;
			val[i][j] += j - ls - 1;
		}
		ls = m;
		for (int j = m - 1; j >= 0; j--) {
			if (mp[i][j] == '#')
				ls = j;
			val[i][j] += ls - j - 1;
		}
	}
	for (int i = 0; i < m; i++) {
		int ls = -1;
		for (int j = 0; j < n; j++) {
			if (mp[j][i] == '#')
				ls = j;
			val[j][i] += j - ls - 1;
		}
		ls = n;
		for (int j = n - 1; j >= 0; j--) {
			if (mp[j][i] == '#')
				ls = j;
			val[j][i] += ls - j - 1;
		}
	}
	int ans = 0;
	for (int i = 0; i < n; i++)
		for (int j = 0; j < m; j++)
			if (mp[i][j] != '#')
				ans = max(ans, val[i][j]);
	cout << ans + 1;
}