#include <iostream>

using namespace std;

int a[20005], N, change;

int main() {
	while (cin >> N) {
		for (int i = 1; i <= N; i++) {
			cin >> a[i];
		}

		change = 0;

		int i = 1;
		while (i <= N) {
			if (i != a[i]) {
				change++;
				int pom = a[i];
				a[i] = a[a[i]];
				a[pom] = pom;
			}
			else
				i++;
		}

		cout << change << endl;
	}
	return 0;
}