#include <iostream>	//cin, cout
#include <vector>	//vector
#include <algorithm> //sort,min,max,count
#include <string>	//string
#include <ios>		//fixed
#include <iomanip>	//setprecision
#include <utility> //swap
#include <cstdlib>	//abs(int)
#include <cmath>	//sqrt
#include <sstream>	//stringstream,getline
#include <cmath>	//ceil

using namespace std;

int main() {

	int N;
	cin >> N;

	vector<int> A(N);
	string temp;

	for (int i = 0; i < N; i++) {
		for (int j = 0; j < N; j++) {
			cin >> temp;
			if (temp == "nyanpass") {
				A[j]++;
			}
		}
	}

	if (count(A.begin(), A.end(), N - 1) == 1) {
		int max_index = distance(A.begin(), max_element(A.begin(), A.end()));
		cout << max_index + 1 << endl;
	}
	else {
		cout << -1 << endl;
	}

	return 0;

}