#include<iostream>
#include<algorithm>
#include <vector>
#include<cmath>
#include<iomanip>
using namespace std;
typedef long long int lont;
int main() {
	int N;
	cin >> N;
	vector<vector<string>>vec(N, vector<string>(N));
	for (int ia = 0; ia < N; ia++) {
		for (int ib = 0; ib < N; ib++) {
			cin >> vec.at(ia).at(ib);
		}
	}
	vector<int>veca(N);
	for (int ic = 0; ic < N; ic++) {
		for (int id = 0; id < N; id++) {
			if (vec.at(id).at(ic) == "nyanpass") {
				veca.at(ic)++;
			}
		}
	}
	int cnt = 0;
	int IE;
	for (int ie = 0; ie < N; ie++) {
		if (veca.at(ie) == N - 1) {
			cnt++;
			IE = ie;
		}
	}
	if (cnt == 1) {
		cout << IE+1 << endl;
	}
	else {
		cout << -1 << endl;
	}
}