#include "bits/stdc++.h"
using namespace std;

int main() {
	int N, X = -1;
	string S;
	bool R[100];
	cin >> N;
	for (int i = 0; i < N; i++) {
		R[i] = true;
	}
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < N; j++) {
			cin >> S;
			if (i != j && S != "nyanpass") R[j] = false;
		}
	}
	for (int i = 0; i < N; i++) {
		if (R[i]) {
			if (X == -1) X = i;
			else X = -2;
		}
	}
	if (X != -1) X++;
	cout << X;
}