#include <iostream>
#include <string>
#include <vector>
using namespace std;

int main(){
	int n;
	cin >> n;
	vector<int> data;
	data.resize(n,0);
	int check = -1;
	/*
	for(auto &a:data){
		cin >> a;
	}
	for(int i = 0; i < n+1; i++){
		if(i % (n+1) == 0) continue;
		if(data[i] == "nyanpass"){
			int count = 1;
			for(int j = i + n; j < n * n; j += n){
				if(data[j] == "nyanpass") count++;
				if(count == n - 1){
					(check == -1) ? (check = (i%n)+1) : (check = -2);
				}
				if(check == -2){
					check = -1;
					break;
				}
			}
		}
	}
	*/

	for(int i = 0;i < n; i++){
		for(int j = 0; j < n; j++){
			string s; cin >> s;
			if(i == j) continue;
			if(s != "nyanpass") data[j] = 1;
		}
	}
	int count = 0;
	for(int j = 0; j < n; j++){
		if(data[j] == 0){
			count++;
			check = j + 1;
		}
	}
	if( count != 1 ) check = -1;
	cout << check << endl;
	return 0;
}