#include<stdio.h>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <algorithm>
#include <sstream>
#include <iostream>
#include <string>
#include <stdio.h>

using namespace std;

int main() {

	int N;
	string S[105][105];

	cin >> N;
	for (int i = 0; i < N; i++) {
		for(int j = 0; j<N; j++) {
			cin >> S[i][j];
		}
	}

	int ans = -1;
	bool flag = false;

	for (int j = 0; j < N; j++) {
		int cnt = 0;
		for (int i = 0; i < N; i++) {
			if (S[i][j] == "nyanpass") {
				cnt++;
			}
		}
		if (cnt == N - 1) {
			if (flag) {
				cout << -1 << endl;
				return 0;
			}
			else {
				ans = j + 1;
				flag = true;
			}
		}
	}

	cout << ans << endl;

	return 0;
}