using System;
using System.Linq;
using System.Collections.Generic;

static class NagataKanaIsAGenius {
    public static void Main() {
        int n=int.Parse(Console.ReadLine());
        if(n<10){
            Console.WriteLine(n);
        }else{
            int x=n/2+5;
            Console.WriteLine(n%2==0?x/10:x%10);
        }
    }
}