using System;

class Program
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        string[,] a = new string[n, n];

        for (int i = 0; i < n; i++)
        {
            string[] s = Console.ReadLine().Split();
            for (int j = 0; j < n; j++)
            {
                a[i, j] = s[j];
            }
        }

        int renchon = -1;
        int cnt = 0;

        for (int j = 0; j < n; j++)
        {
            for (int i = 0; i < n; i++)
            {
                if (a[i, j] == "nyanpass") cnt++;
            }

            if (cnt == n - 1)
            {
                if (renchon != -1)
                {
                    Console.WriteLine(-1);
                    return;
                }
                else renchon = j + 1;
            }

            cnt = 0;
        }

        Console.WriteLine(renchon);
    }
}