#nullable enable

#region
var (_input, _iter) = (Array.Empty<string>(), 0);
T I<T>() where T : IParsable<T>
{
    while (_iter >= _input.Length) (_input, _iter) = (Console.ReadLine()!.Trim().Split(' '), 0);
    return T.Parse(_input[_iter++], null);
}
#endregion

static T[] Range<T>(int n, Func<T> F) => Enumerable.Range(0, n).Select(_ => F()).ToArray();

var n = I<int>();
var az = Range(n, () => I<int>() - 1);

var uf = new UnionFind(n);
for (var i = 0; i < n; i++) uf.Union(i, az[i]);

var ans = 0;
for (var i = 0; i < n; i++) if (uf.Find(i) == i) ans++;
Console.WriteLine(ans);

class UnionFind
{
    int[] Verticals { get; set; }
    public UnionFind(int verticals)
    {
        Verticals = new int[verticals];
        Verticals.AsSpan().Fill(-1);
    }

    public int Union(int x, int y)
    {
        (x, y) = (Find(x), Find(y));
        if (x == y) return x;
        var (sx, sy) = (Size(x), Size(y));
        if (sx < sy) (x, y, sy) = (y, x, sx);
        Verticals[x] -= sy;
        return Verticals[y] = x;
    }

    public int Find(int x)
    {
        var p = Verticals[x];
        if (p < 0) return x;
        return Verticals[x] = Find(p);
    }

    public int Size(int x) => -Verticals[Find(x)];
}