#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <math.h>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <math.h>
#include <iostream> 
#include<map>
#include <iomanip>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
using namespace std;
#define MAX_MOD 1000000007
#define REP(i,n) for(long long i = 0;i < n;++i)
#define LONG_INF 100000000000000
int ren[1000] = {};
int main() {
	int n;
	cin >> n;
	REP(i, n) {
		ren[i] = true;
	}
	REP(i, n) {
		REP(q, n) {
			string s;
			cin >> s;
			if (s != "-") {
				if (s != "nyanpass") {
					ren[q] = false;
				}
			}
		}
	}
	int wow = -1;
	for (int i = 0;i < n;++i) {
		if (ren[i] == true) {
			if (wow != -1) {
				cout << "-1" << endl;
				return 0;
			}
			wow = i;
		}
	}
	cout << wow+1 << endl;
	return 0;
}