using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        string input = Console.ReadLine();

        Char[] charin = input.ToCharArray();

        List<char> charlist = new List<char>();

        bool found = false;

        charlist.AddRange(charin);

        //for(int i=0; i<charin.Length;i++){

        //  for(int j=i; j<charin.Length;j++){

        //if(charlist.IndexOf(charlist[j],j)!=-1){

        //  found = true;

        //break;

        //  break;

        //}

        //}

        //}

        int length = charlist.Count;

        char searching;

        while (length != 0)

        {

            searching = charlist[0];

            charlist.RemoveAt(0);

            for (int j = 0; j < length; j++)

            {

                if (charlist.IndexOf(searching) != -1)

                {

                    found = true;

                    //break;

                    break;

                }

​

                length = charlist.Count;

            }

        }

​

        if (found == true)

        {

            Console.Write("not iso");

        }

        else

        {

            Console.Write("iso");

        }

    }

}