#include <iostream>
using namespace std;
 
int main(){
	int N;
	cin >> N;
	bool if_nyantyon[N];
	for(int i = 0; i < N; i++){
		if_nyantyon[i] = true;
	}
	for(int i = 0; i < N; i++){
		for(int j = 0; j < N; j++){
			string hello;
			cin >> hello;
			if(hello != "nyanpass" && hello != "-"){
				if_nyantyon[j] = false;
			}
		}
	}
	int ans = -1;
	for(int i = 0; i < N; i++){
		if(if_nyantyon[i]){
			if(ans == -1){
				ans = i + 1;
			}else{
				cout << -1 << endl;
				return 0;
			}
		}
	}
	cout << ans << endl;
}