using System;
class Program
{
    static void Main(string[] args)
    {
        int total = int.Parse(Console.ReadLine()!);
        string[,] wordArray = new string[total, total]; 

        for (int i = 0; i < total; i++)
        {
            string[] input = Console.ReadLine()!.Split(' ');
            for (int j = 0; j < input.Length; j++)
            {
                wordArray[i, j] = input[j];
            }
        }

        int ans = 0;
        int count = 0;
        for (int i = 0;i < total; i++)
        {
            int wordCount = 0;
            for (int j = 0; j < total; j++)
            {
                if (wordArray[j, i] == "nyanpass" || wordArray[j, i] == "-")
                {
                    wordCount++;
                }
            }
            if (wordCount == total)
            {
                count++;
                ans = i + 1;
            }
        }

        if (count == 1 && ans != 0)
        {
            Console.WriteLine(ans);
        }
        else
        {
            Console.WriteLine(-1);
        }
    }
}