#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
using namespace std;
using pii = pair<int, int>;
using ll = long long;

int main() {
	int n, m;
	cin >> n >> m;
	vector<string> s(n);
	rep(i, n) cin >> s[i];

	vector<int> cnt(m);
	rep(i, n) {
		rep(j, m) {
			if (s[i][j] == 'x') cnt[j]++;
		}
	}
	sort(cnt.rbegin(), cnt.rend());

	int ans = cnt[0] + 1;
	cout << ans << endl;
	return 0;
}