using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace yukicoderTest
{
    class Program
    {
        static void Main(string[] args)
        {
            string input = Console.ReadLine();
            int n = int.Parse(input);
            int[] cnt = new int[n];
            for (int i = 0; i < n; i++)
            {
                string[] aisatu = Console.ReadLine().Split(' ');
                for (int j = 0; j < n; j++)
                {
                    if (aisatu[j] == "nyanpass")
                    {
                        cnt[j]++;
                    }
                }
            }
            int max = -100;
            int ren = -1;
            bool flg = false;
            for (int i = 0; i < n; i++)
            {
                if (cnt[i]==n-1&&flg==false)
                {
                    max = cnt[i];
                    ren = i;
                    flg = true;
                }
                else if (cnt[i] == max&&flg==true)
                {
                    ren = -1;
                    break;
                }
            }
            if (ren != -1)
            {
                Console.WriteLine(ren + 1);
            }
            else
            {
                Console.WriteLine(ren);
            }
        }

    }
}