#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <iostream>
#include <queue>
#include <list>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;

int N;
string v[105][105];

int solve(){
  int ret = -1;

  rep(j,N){
    bool flg = true;
    rep(i,N){
      if(j==i) continue;
      if(v[i][j] != "nyanpass") flg = false;
    }
    if(flg){
      if(ret >= 0) return -1;
      ret = j+1;
    }
  }
  return ret;
}


int main(){
  cin >> N;
  rep(i,N){
    rep(j,N){
      cin >> v[i][j];
    }
  }

  cout << solve() << endl;
  
  return 0;
}