#include <iostream> // cout, endl, cin
#include <string> // string, to_string, stoi
#include <vector> // vector
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <utility> // pair, make_pair
#include <tuple> // tuple, make_tuple
#include <cstdint> // int64_t, int*_t
#include <cstdio> // printf
#include <map> // map
#include <queue> // queue, priority_queue
#include <set> // set
#include <stack> // stack
#include <deque> // deque
#include <unordered_map> // unordered_map
#include <unordered_set> // unordered_set
#include <bitset> // bitset
#include <cctype> // isupper, islower, isdigit, toupper, tolower
#include <math.h>
#include <cmath>
using namespace std;

#define int long long
#define endl "\n"
#define all(v)  v.begin(),v.end()
#define fir first
#define sec second
#define m_p make_pair
#define rep(i,n)  for(int i=0; i<(int) (n); i++)
#define vecin(v) for(int i=0; i<(int)v.size(); i++)cin>>v[i];
#define vecout(v,n) for(int i=0; i<n; i++)cout<<v[i]<<" "; cout<<endl;

const int mod = 1000000007;
const int INF = 2000000015;
const int MAX = 510000;
const int MOD = 1000000007;
long long fac[MAX], finv[MAX], inv[MAX];
int jousu(int x00, int y00) {
	int z00 = 1;
	for (int i = 0; i < y00; i++) {
		z00 *= x00;
	}
	return z00;
}
int keta(int x00) {
	int z00 = x00;
	int w00 = 0;
	while (z00 != 0) {
		z00 /= 10;
		w00++;
	}
	return w00;
}
int krag(double xx) {
	return INF - (int)(INF - xx);
}


int modinv(int a, int m) {
	int b = m, u = 1, v = 0;
	while (b) {
		int t = a / b;
		a -= t * b; swap(a, b);
		u -= t * v; swap(u, v);
	}
	u %= m;
	if (u < 0) u += m;
	return u;
}
int modpow(int a, int n) {
	int res = 1;
	while (n > 0) {
		if (n & 1) res = res * a % mod;
		a = a * a % mod;
		n >>= 1;
	}
	return res;
}
int com(int xx, int yy) {
	int zz = 1;
	for (int i = xx; i > xx - yy; i--) {
		zz *= i;
		zz %= mod;
	}
	for (int i = 1; i <= yy; i++) {
		zz *= modinv(i, mod);
		zz %= mod;
	}
	return zz;
}
int gcd(int xx, int yy) {
	int p = xx;
	int q = yy;
	if (q > p)swap(p, q);
	while (p % q != 0) {
		p %= q;
		swap(p, q);
	}
	return q;
}
int lcm(int xx, int yy) {
	return xx * yy / gcd(xx, yy);
}
bool prime(int xx) {
	int a = xx;
	for (int i = 2; i * i <= xx; i++) {
		if (xx % i == 0) {
			return 0;
		}
	}
	return 1;
}




signed main() {
	int h, w, c, ans = 0;
	cin >> h >> w;
	vector<vector<char>>vec(h, vector<char>(w));
	vector<vector<int>>vec2(h, vector<int>(w));
	rep(i, h) {
		rep(j, w) {
			cin >> vec[i][j];
		}
	}
	rep(i, h) {
		rep(j, w) {
			if (vec[i][j] == '.') {
				c = 0;
				while (j < w && vec[i][j] == '.') {
					c++;
					vec2[i][j] += c;
					j++;
				}
			}
		}
	}
	rep(i, h) {
		for (int j = w - 1; j >= 0; j--) {
			if (vec[i][j] == '.') {
				c = 0;
				while (j >= 0 && vec[i][j] == '.') {
					vec2[i][j] += c;
					c++;
					j--;
				}
			}
		}
	}
	rep(i, w) {
		rep(j, h) {
			if (vec[j][i] == '.') {
				c = 0;
				while (j < h && vec[j][i] == '.') {
					c++;
					vec2[j][i] += c;
					j++;
				}
			}
		}
	}
	rep(i, w) {
		for (int j = h - 1; j >= 0; j--) {
			if (vec[j][i] == '.') {
				c = 0;
				while (j >= 0 && vec[j][i] == '.') {
					vec2[j][i] += c;
					c++;
					j--;
				}
			}
		}
	}
	rep(i, h) {
		rep(j, w) {
			if (ans < vec2[i][j]) {
				ans = vec2[i][j];

			}
			ans = max(vec2[i][j], ans);
		}
	}
	cout << ans-1 << endl;

}



Measured memory_bytes: 35584