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

int main(){
	int n;
	cin >> n;
	int talk[n];
	fill(talk, talk + n, 0);
	string str;
	for(int i = 0; i < n; i++){
		for(int i = 0; i < n; i++){
			cin >> str;
			if(str == "nyanpass")talk[i]++;
		}
	}
	int renchon = 0;
	for(int i = 0; i < n; i++){
		if(talk[i] == n - 1)renchon++;
	}
	if(renchon == 1){
		for(int i = 0; i < n; i++){
			if(talk[i] == n - 1)cout << i + 1 << endl;
		}
	}else{
		cout << "-1" << endl;
	}
}