/*
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 * and open the template in the editor.
 */
package amusement;

import java.util.Scanner;

/**
 *
 * @author hlavaty7
 */
public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int size;
        int[] pole;
        while (sc.hasNext()) {
            size = sc.nextInt();

            pole = new int[size];

            for (int i = 0; i < pole.length; i++) {
                pole[i] = sc.nextInt();
            }

            int vykonaj = vykonaj(pole);
            System.out.println(vykonaj);

        }

    }

    private static int vykonaj(int[] pole) {
        int c = 0;
        int i = 0;
        while (i < pole.length) {
            if (pole[i] != i + 1) {
                int tmp = pole[i];
                int index = pole[i];
                pole[i] = pole[index - 1];
                pole[index - 1] = tmp;
                
                c++;
            }
            if(pole[i] == i+1){
                i++;
            }
        }
        return c;
    }

}