#include <stdio.h>

int main() {
	int n = 0;
	int arr[200000];
	bool swapped[200000];
	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 toAdd = (goodPosCount + 2 * pairPosCount != n ? -1 : 0);
		printf("%d\n", n - goodPosCount - pairPosCount + toAdd);
	}

	return 0;
}