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 a = NList;
        var uf = new UnionFindTree(n);
        for (var i = 0; i < n; ++i)
        {
            uf.Unite(i, a[i] - 1);
        }
        var ans = 0;
        for (var i = 0; i < n; ++i)
        {
            if (uf.GetRoot(i) == i) ans += uf.GetSize(i) - 1;
        }
        WriteLine(ans);
    }
    class UnionFindTree
    {
        int[] roots;
        public UnionFindTree(int size)
        {
            roots = new int[size];
            for (var i = 0; i < size; ++i) roots[i] = -1;
        }
        public int GetRoot(int a)
        {
            if (roots[a] < 0) return a;
            return roots[a] = GetRoot(roots[a]);
        }
        public bool IsSameTree(int a, int b)
        {
            return GetRoot(a) == GetRoot(b);
        }
        public bool Unite(int a, int b)
        {
            var x = GetRoot(a);
            var y = GetRoot(b);
            if (x == y) return false;
            if (-roots[x] < -roots[y]) { var tmp = x; x = y; y = tmp; }
            roots[x] += roots[y];
            roots[y] = x;
            return true;
        }
        public int GetSize(int a)
        {
            return -roots[GetRoot(a)];
        }
    }
}