#include "bits/stdc++.h"
using namespace std;

#define DEBUG(x) cout<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cout<<#v<<":";for(int i=0;i<v.size();i++) cout<<" "<<v[i]; cout<<endl

typedef long long ll;
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
#define fi first
#define se second
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rep1(i,n) for(int i=1;i<=(int)(n);i++)
#define all(c) c.begin(),c.end()
const int inf = 1000000001;
const ll INF = 2e18;
const ll MOD = 1000000007;
const ll mod = 1000000009;
const double pi = 3.14159265358979323846;
#define Sp(p) cout<<setprecision(15)<< fixed<<p<<endl;
int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 };
int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };

int main() {
	int n;
	cin >> n;
	vector<vector<string> > a(n, vector<string>(n));
	rep(i, n) {
		rep(j, n) {
			cin >> a[i][j];
		}
	}
	int nya = -1;
	rep(j, n) {
		bool flag = true;
		rep(i, n) {
			if (i == j) {
				continue;
			}
			if (a[i][j] != "nyanpass") {
				flag = false;
				break;
			}
		}
		if (flag) {
			if (nya == -1) {
				nya = j + 1;
			}
			else {
				cout << -1 << endl;
				return 0;
			}
		}
	}
	cout << nya << endl;
}