#include <iostream>
#include <algorithm>
#include <vector>
#include <deque>
#include <string>
#include <tuple>
#include <functional>
#include <numeric>
#include <cmath>
#include <iomanip>
#include <map>
#include <random>
//#include "toollib.h"
#define INT_MAX 2147483647
#define Loop(i, n) for(int i = 0; i < (int)n; i++)
#pragma warning (disable:4018)

using namespace std;
typedef long long int lint;

//***** Main Program *****

int main() {
	const string key = "nyanpass";
	int N;
	cin >> N;
	vector<vector<string>> A(N, vector<string>(N));
	Loop(i, N) {
		Loop(j, N) {
			cin >> A[i][j];
		}
	}
	int ret = 0;
	Loop(j, N) {
		bool judge = true;
		Loop(i, N) {
			if (i != j&&A[i][j] != key) {
				judge = false;
				break;
			}
		}
		if (judge) {
			if (ret == 0) ret = j + 1;
			else ret = -1;
		}
	}
	if (ret == 0) ret = -1;
	cout << ret << endl;
}