/* -*- coding: utf-8 -*-
 *
 * 239.cc: No.239 にゃんぱすー - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 100;

/* typedef */

/* global variables */

string as[MAX_N][MAX_N];

/* subroutines */

/* main */

int main() {
  int n;
  cin >> n;

  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) cin >> as[i][j];

  int mi = -1;
  for (int j = 0; j < n; j++) {
    bool ok = true;
    for (int i = 0; i < n; i++)
      if (i != j && as[i][j] != "nyanpass") {
	ok = false;
	break;
      }

    if (ok) {
      if (mi >= 0) {
	mi = -1;
	break;
      }
      mi = j + 1;
    }
  }

  printf("%d\n", mi);
  return 0;
}