#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>
#include <vector>
#include <map>
#include <set>
#include <algorithm>
#include <string>
#include <cstdlib>
#include <stack>
#include <queue>
#include <cmath>

#define rep(i,j,k) for(int i=(int)j;i<(int)k;i++)
#define repp(i,j,k) for(int i=j;i>=k;i--)
#define Sort(x) sort(x.begin(),x.end()); 
#define ll long long
int mod=1e9+7;
const int INF = 1e9;

using namespace std;


int main(void) {
	int n;
	cin >> n;
	vector<bool> v(n, true);
	rep(i, 0, n) {
		rep(j, 0, n) {
			string s;
			cin >> s;

			if (s != "nyanpass" && s!="-") v[j] = false;
		}
	}
	int judge = 0,ans;
	rep(i, 0, n) {
		if (v[i]) {
			judge++;
			ans = i + 1;
		}
	}
	if (judge==1) cout << ans << endl;
	else cout << -1 << endl;

	return 0;
}