using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var p = NList;
        var refs = new int[n + 1];
        for (var i = 0; i < n; ++i) ++refs[p[i]];
        var ans = new bool[n + 1];
        for (var i = 1; i <= n; ++i) if (refs[i] == 0)
            {
                var pa = p[i - 1];
                if (pa > 0) ans[p[pa - 1]] = true;
            }
        WriteLine(ans.Skip(1).Count(f => f));
    }
}