#include<bits/stdc++.h>
using namespace std;
using Int = long long;

template<typename T>
vector<T> make_v(size_t a){return vector<T>(a);}

template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts){
  return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}

template<typename T,typename V>
typename enable_if<is_class<T>::value==0>::type
fill_v(T &t,const V &v){t=v;}

template<typename T,typename V>
typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t,const V &v){
  for(auto &e:t) fill_v(e,v);
}

//INSERT ABOVE HERE
signed main(){
  Int n;
  cin>>n;
  auto a=make_v<string>(n,n);
  for(Int i=0;i<n;i++)
    for(Int j=0;j<n;j++)
      cin>>a[i][j];

  Int ans=-1;
  string b="nyanpass";
  for(Int j=0;j<n;j++){
    Int flg=1;
    for(Int i=0;i<n;i++){
      if(i==j) continue;
      flg&=a[i][j]==b;
    }
    if(flg&&~ans){
      ans=-1;
      break;
    }
    if(flg) ans=j+1;
  }

  cout<<ans<<endl;
  return 0;
}