using System;
using System.Linq; // 追加

public class Program {
	public void Solve() {
		int N = int.Parse(Console.ReadLine());
		int[] arr = new int[N];
		string[] A;
		for (int i = 0; i < N; i++) {
			A = Console.ReadLine().Split(' ');
			for (int j = 0; j < N; j++) {
				if (A[j].Equals("nyanpass")) {
					arr[j]++;
				}
			}	
		}
		if (arr.Where(x => x == N - 1).Count() == 1) {
			Console.WriteLine(Array.IndexOf(arr, N - 1) + 1);
		} else {
			Console.WriteLine(-1);
		}
	}
	
	public static void Main(string[] args) {
		Program solver = new Program();
		solver.Solve();
	}
}