#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <algorithm>
#include <sstream>
#include <map>
#include <set>
#include <cstdio>
using namespace std;

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
/* ここからが本編 */
/* */
/* 入力開始！ */
/* 入力終了！ */
int main(void)
{
  int i,j,k,l;
  int n;
  static char a[100][100][35];
  char now_renchon;
  int renchon = -1;
  scanf("%d",&n);
  rep(i,n) {
    rep(j,n) scanf("%s",a[i][j]);
  }
  for(j=0;j<n;j++) {
    now_renchon = 1;
    for(i=0;i<n;i++) {
      if(i == j) continue;
      if(strcmp(a[i][j],"nyanpass") != 0) {
        now_renchon = 0;break;
      }
    }
    if(now_renchon && renchon > -1) {
      renchon = -1; break;
    }
    if(now_renchon && renchon == -1) {
      renchon= j+1;
    }
  }
  printf("%d\n",renchon); 
  return 0;
}