#include <iostream>
#include <string>
using namespace std;

int main(){
   int count,n,p = -1; cin >> n;
   int v[n];
   string s[n][n];
   for(int i = 0;i < n;i++){
      for(int j = 0;j < n;j++){
         cin >> s[i][j];
         if(s[i][j] == "nyanpass") v[j]++;
      }
   }
   for(int i = 0;i < n;i++){
      if(v[i] == n - 1){
         if(p == -1) p = i + 1;
      }else{
         p = -1;
         break;
      }
   }
   cout << p << endl;
}