using System;
using System.Collections.Generic;
using System.Linq;

public class P0239 {
    public static void Main() {
        var n = int.Parse(Console.ReadLine().Trim());
        var cands = Enumerable.Range(0, n).Select(i => true).ToList();
        for(int i=0; i<n; i++){
            var line = Console.ReadLine().Trim().Split(' ').ToList();
            for(int j=0; j<n; j++) {
                if(i != j) {
                    cands[j] &= line[j] == "nyanpass";
                }
            }
        }
        if(cands.Where(c => c).Count() == 1) {
            Console.WriteLine(Enumerable.Range(1, n).Zip(cands, (i, j) => new { left = i, right = j }).Where(pair => pair.right).Select(pair => pair.left).First());
        } else {
            Console.WriteLine(-1);
        }
    }
}