#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef complex<double> P;
typedef pair<int,int> pii;
#define REP(i,n) for(ll i=0;i<n;++i)
#define REPR(i,n) for(ll i=1;i<n;++i)
#define FOR(i,a,b) for(ll i=a;i<b;++i)

#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl
#define ALL(a) (a).begin(),(a).end()

#define MOD (ll)(1e9+7)
#define ADD(a,b) a=((a)+(b))%MOD
#define FIX(a) ((a)%MOD+MOD)%MOD

int main(){
  int n;
  cin >> n;
  vector<bool> flag(n,true);
  string renchon = "nyanpass";
  REP(i,n){
    REP(j,n){
      string s;
      cin >> s;
      if(i==j)continue;
      if(s!=renchon)flag[j]=false;
    }
  }
  int pasu = -2;
  REP(i,n){
    if(pasu==-2 && flag[i])pasu = i;
    else if(flag[i]){
      pasu = -2;
      break;
    }
  }
  cout << pasu+1 << endl;
  return 0;
}