#include <stdio.h>

int main(){
	int n;
	while(scanf("%d", &n) + 1){
		int arr[n];
		for(int i = 0; i < n; i++){
			scanf("%d", &arr[i]);
			arr[i]--;
		}
		int swaps = 0;
		for(int i = 0; i < n;){
			if(i != arr[i]){
				swaps++;
				int tmp = arr[arr[i]];
				arr[arr[i]] = arr[i];
				arr[i] = tmp;
			} else {
				i++;
			}
		}
		printf("%d\n", swaps);
	}
	return 0;
}