using System;

namespace yukicoder
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = int.Parse(Console.ReadLine());
            string[,] b = new string[a,a];
            int[] c = new int[a];
            int d=0;
            int count = 0;
            int ans=0;
            for(int i = 0; i < a; i++)
            {
                string[] s = Console.ReadLine().Split(' ');
                for(int j = 0; j < a; j++)
                {
                    b[i,j ] = s[j];
                }
            }
            for (int i = 0; i < a; i++)
            {
                for (int j = 0; j < a; j++)
                {
                    if(b[j, i]=="nyanpass")
                    {
                        count++;
                    }
                }
                if(count == a-1&&d<1)
                {
                    d++;
                    ans = i+1;
                }
                else if(count == a-1&& d >= 1)
                {
                    d++;
                }
                if (ans == 0 || d > 1)
                {
                    ans = -1;
                }
                count = 0;
            }

            Console.WriteLine(ans);
        }
    }
}