#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <numeric>
#include <bitset>
#include <complex>
#define rep(x, to) for (int x = 0; x < (to); x++)
#define REP(x, a, to) for (int x = (a); x < (to); x++)
#define foreach(itr, x) for (typeof((x).begin()) itr = (x).begin(); itr != (x).end(); itr++)
#define EPS (1e-14)

using namespace std;

typedef long long ll;
typedef pair<int, int> PII;
typedef pair<ll, ll> PLL;
typedef complex<double> Complex;
typedef vector< vector<int> > Mat;

int N;
int renge[105];
string s;

int main() {
	cin >> N;
	rep(i, N) rep(j, N) {
		cin >> s;
		if (s == "nyanpass") {
			renge[j]++;
		}
	}
	int mx = -1;
	rep(i, N) mx = max(mx, renge[i]);
	if (mx != N-1) {
		cout << -1 << endl;
		return 0;
	}
	int cnt = 0, idx = 0;
	rep(i, N) {
		if (mx == renge[i]) {
			cnt++;
			idx = i+1;
		}
	}
	if (cnt != 1) {
		cout << -1 << endl;
	} else {
		cout << idx << endl;
	}
	return 0;
}