#!/bin/python3

import math
import os
import random
import re
import sys

# Complete the minimumSwaps function below.

def minimumSwaps(arr, n):
    c = 0
    i = 0
    while i < n - 1:
        if arr[i] - 1 != i:
            arr[arr[i] - 1], arr[i] = arr[i], arr[arr[i] - 1]
            c += 1
            i = 0
        else:
            i += 1

    return c

if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    n = int(input())

    arr = list(map(int, input().rstrip().split()))

    res = minimumSwaps(arr, n)

    fptr.write(str(res) + '\n')

    fptr.close()