//package ctu;

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while (true) {
            int pocet_komnat = sc.nextInt();
            int[] komnata = new int[pocet_komnat + 1];

            boolean vsetkoOk = true;
            for (int i = 1; i <= pocet_komnat; i++) {
                komnata[i] = sc.nextInt();
                if (komnata[i] != i) {
                    vsetkoOk = false;
                }
            }

            int pocet_swapov = 0;

            if (!vsetkoOk) {
                for (int k = 1; k <= pocet_komnat; k++) {
                    if (k != komnata[k]) {
                        for (int p = k + 1; p <= pocet_komnat; p++) {
                            if (k == komnata[p]) {
                                komnata[p] = komnata[k];
                                komnata[k] = k;
                                pocet_swapov++;
                                //vypis(komnata);
                                break;
                            }
                        }
                    }
                }
            }

            System.out.println(pocet_swapov);

        }

    }
    
    private static void vypis(int[] komnata) {
        System.out.println("==============================");
        for (int i = 1; i < komnata.length; i++) {
            System.out.println(i + " " + komnata[i]);
        }
        System.out.println("==============================");
    }

}