#include <bits/stdc++.h>

#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define endl "\n"
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define rrep(i, n) for(int i = ((int)(n)-1); i >= 0; i--)
#define all(x) (x).begin(),(x).end()

using namespace std;
using ll = long long;

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> P;
 
const int INF = 1e9;
//const ll INF = 1e18;
const double EPS = 1e-10;
const int MOD = 1e9+7;
const double PI = acos(-1.0);

int main()
{
	int n;
	cin >> n;
	string s[n+10][n+10];
	rep(i,n) rep(j,n) cin >> s[i][j];
	int cnt = 0,ans = 0;
	for(int i = 0; i < n; i++){
		for(int j = 0; j <= n; j++){
			if(j == n){
				cnt++;
				ans = i+1;
				break;
			}
			if(i == j) continue;
			if(s[j][i] != "nyanpass") break;
		}
	}
	cout << (cnt != 1 ? -1 : ans) << endl;
	return 0;
}