#include<iostream>
#include<string>
#include<cstring>
#include<complex>
#include<vector>
#include<algorithm>
#include<cstdlib>
#include<cmath>
#include<iomanip>
using namespace std;

#define REP(i, j) for (int i = 0; i < (int)j; ++i)
#define FOR(i, j, k) for (int i = (int)j; i < (int)k; ++i)
#define SORT(v) sort(v.begin(), v.end())
#define REVERSE(v) reverse(v.begin(), v.end())
typedef complex<double> P;
typedef vector<int> VI;
typedef long long LL;
typedef pair<int,int> PII;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int n;
	cin >> n;
	vector<vector<string>> v(n, vector<string>(n));
	REP(i,n) {
		REP(j,n) {
			string a;
			cin >> a;
			v[i][j] = a;
		}
	}

	VI ncnt(n,0);
	REP(j,n) {
		REP(i,n) {
			if (v[i][j] == "nyanpass") ncnt[j]++;
		}
	}

	int cnt = 0, ans;
	REP(i,n) {
		if (ncnt[i] == (n - 1)) {
			cnt++;
			ans = i + 1;
		}
	}

	if (cnt == 1) cout << ans << endl;
	else cout << -1 << endl;

	return 0;
}