#include <stdio.h>

int max(int a1, int a2) {
	return a1 > a2 ? a1 : a2;
}

int main() {
	int n = 0;
	int arr[300000];
	bool swapped[300000];
	while (scanf("%d", &n) > 0) {
		for (int i = 0; i < n; i++) {
			scanf("%d", &arr[i]);
			swapped[i] = false;
		}
		
		int goodPosCount = 0;
		for (int i = 0; i < n; i++) {
			if (arr[i] == i + 1) goodPosCount++;
		}		

		int pairPosCount = 0;
		for (int i = 0; i < n; i++) {
			if (arr[i] != i + 1 && arr[arr[i] - 1] == i + 1 && swapped[i] == false) {
				pairPosCount++;
				swapped[i] = true;
				swapped[arr[i] - 1] = true;
			}
		}
		
		int res = pairPosCount + max(0, n - goodPosCount - 2 * pairPosCount - 1);
		//int res = n - goodPosCount - pairPosCount + (goodPosCount + 2 * pairPosCount != n ? -1 : 0);
		printf("%d\n", res);
	}

	return 0;
}