#include <iostream>

using namespace std;


int main()
{
    std::ios_base::sync_with_stdio(false);

    while(true)
    {
        int pocet;
        bool cont = false;
        bool swapped = false;
        int swaps = 0;

        cin >> pocet;
        if(cin.eof())
            break;

        int* cisla = new int[pocet];

        for(int i = 0; i < pocet; i++)
        {
            cin >> cisla[i];
            cisla[i]--;
        }

        while(true)
        {
            cont = false;
            for(int i = 0; i < pocet; i++)
            {
                if(cisla[i] != i && cisla[cisla[i]] == i)
                {
                    swap(cisla[i], cisla[cisla[i]]);
                    swaps++;
                    cont = true;
                }
            }
            if(cont)
                continue;

            swapped = false;
            for(int i = 0; i < pocet; i++)
            {
                if(cisla[i] != i)
                {
                    swap(cisla[i], cisla[cisla[i]]);
                    swaps++;
                    swapped = true;
                    break;
                }
            }
            if(!swapped)
                break;
        }

        cout << swaps << endl;
    }


    return 0;
}