#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <fstream>

using namespace std;

int main(void) {
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);
	std::cout << std::fixed;
	int N;
	vector<int> A(100);
	cin >> N;
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < N; j++) {
			string L;
			cin >> L;
			if (L == "nyanpass") {
				A[j]++;
			}
		}
	}
	int index = -1;
	for (int i = 0; i < N; i++) {
		if (A[i] == N - 1) {
			if (index == -1)
				index = i + 1;
			else
				index = -2;
		}
	}
	cout << ((index < 0) ? -1 : index) << endl;
}