#include <bits/stdc++.h>
using namespace std;
typedef int64_t ll;


void solve() {
  ll n;
  cin>>n;
  string s="nyanpass";
  vector<vector<string>> a(n, vector<string>(n));
  for (ll i = 0; i < n; i++) {
    for (ll j = 0; j < n; j++) {
      cin >> a[i][j];
    }
  }
  vector<bool> answer(n, true);
  for (ll i = 0; i < n; i++) {
    for (ll j = 0; j < n; j++) {
      if(i!=j&&a.at(i).at(j)!=s){ 
        answer.at(j)=false;
      }
    }
  }
  ll cnt=0;
  for(ll i=0;i<n;i++){
    if(answer.at(i)) cnt++;
  }
  if(cnt!=1){
    cout<<-1<<endl;
  }else{
    for(ll i=0;i<n;i++){
      if(answer.at(i)) {
        cout<<i+1<<endl;
        break;
      }
    }
  }
} 

int main() { solve();system("pause"); }