import java.util.*;
import java.util.stream.*;

import static java.lang.Math.*;

public class Main {
  private void solve() {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    sc.nextLine();
    String[][] mat = new String[n][n];
    int[] nyan = new int[n];
    for(int r=0; r<n; r++) {
      String line = sc.nextLine();
      String[] sp = line.split(" ");
      for(int c=0; c<n; c++) {
        mat[r][c] = sp[c];
      }
    }
    for(int r=0; r<n; r++) {
      for(int c=0; c<n; c++) {
        if(mat[r][c].equals("nyanpass")) { nyan[c]++; }
      }
    }
    int cnt = 0, res = -1;
    for(int i=0; i<n; i++) {
      if(nyan[i] == n-1) { cnt++; res = i+1; }
    }
    System.out.printf("%d\n", cnt==1?res:-1);
  }

  public static void main(String[] args) {
    new Main().solve();
  }
}