#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <set>
using namespace std;

const string x = "nyanpass";

int main(){
	int n;
	cin >> n;
	vector<vector<string>> s(n, vector<string>(n));
	for(int i=0; i<n; i++){
		for(int j=0; j<n; j++){
			cin >> s[i][j];
		}
	}
	int cnt = 0;
	int num = -1;
	for(int i=0; i<n; i++){
		bool ok = true;
		for(int j=0; j<n; j++){
			if(i==j) continue;
			if(s[j][i] != x){
				ok = false;
				break;
			}
		}
		if(ok){
			num = i;
			cnt++;
		}
	}

	if(cnt == 1){
		cout << num+1 << endl;
	}else{
		cout << -1 << endl;
	}


	return 0;
}