#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main() {
	int N;
	int ans = -1;
	cin >> N;
	vector<int> v(N, 0);
	vector<vector<string> > A(N, vector<string>(N));
	for (int i = 0; i < N;i++) {
		for (int j = 0;j < N;j++) {
			cin >> A[i][j];
			if (A[i][j] == "nyanpass") {
				v[j]++;
			}
		}
	}
	for (int i = 0; i < N;i++) {
		if (v[i] == N - 1) {
			if (ans == -1) {
				ans = i + 1;
			}
			else {
				cout << -1 << endl; return 0;
			}
		}
	}
	cout << ans << endl;
	return 0;
}