using System.Linq;
using System;

public class Hello
{
    public static void Main()
    {
        var n = int.Parse(Console.ReadLine().Trim());
        var a = new int[n];
        for (int i = 0; i < n; i++)
        {
            string[] line = Console.ReadLine().Trim().Split(' ');
            for (int j = 0; j < n; j++)
                if (line[j] == "nyanpass") a[j]++;
        }
        var b = a.Count(x => x == n - 1);
        if (b == 0 | b >= 2)  Console.WriteLine(-1); 
        else
            for (int i = 0; i < n; i++)
                if (a[i] == n - 1) { Console.WriteLine(i  + 1); break; }
    }
}