#include <bits/stdc++.h>
#include <iostream>
#include <string>
using namespace std;

int main() {
	int n;
	cin >> n;
	string s[n][n];

	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < n; ++j) {
			cin >> s[i][j];
		}
	}
	int count = 0;
	map<int, int> m;
	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < n; ++j) {
			if (s[i][j] == "nyanpass") {
				m[j]++;
			}
		}
	}
int ans=0;
	for (int j = 0; j < n; ++j) {
		if (m[j] == n - 1 && count == 0) {
			count++;
			ans=j;
		} else if (m[j] == n - 1 && count == 1) {
			cout << -1 << endl;
			return 0;
		}
	}
	if (count == 1) {
		cout << ans + 1 << endl;
	} else {
		cout << -1 << endl;
		return 0;
	}

}