using System;
using System.Linq;

namespace _03.Wormhole
{
    class Program
    {
        static void Main(string[] args)
        {
            var inputLine = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            var counter = 0;

            for (int i = 0; i < inputLine.Length; i++)
            {
                counter++;
                if (inputLine[i] != 0)
                {
                    var temp = i;
                    i = inputLine[i];
                    inputLine[temp] = 0;
                }
            }
            Console.WriteLine(counter);
        }
    }
}