using System.Numerics;

public class Program
{
    public static void Main()
    {

        //int num = int.Parse(Console.ReadLine() ?? string.Empty);
        //string[] str = (Console.ReadLine() ?? string.Empty).Trim().Split(' ');
        //string str = Console.ReadLine() ?? string.Empty;

        BigInteger a = BigInteger.Parse(Console.ReadLine() ?? string.Empty);

        BigInteger g = a / 3;

        BigInteger b = (a % 3)/2;

        Console.WriteLine(b);
    }
}