#include <stdio.h>

int main() {

	int n;

	while (scanf("%d",&n) == 1) {

		if (n == 1) {
			scanf("%d",&n);
			printf("0\n");
			continue;
		}

		int i;
		int array[n+1];
		for (i = 1; i < n+1; i++) {
			scanf("%d",&array[i]);
		}

		i = 1;
		int c = 0;
		while(i < n+1){
			if(array[i] == i) {
				//printf("Moving to next number\n");
				i++;
			} else {
				int index1 = i;
				int index2 = array[i];
				int temp = array[index1];
				//printf("Swapping %d <-> %d\n", array[index1], array[index2]);
				array[index1] = array[index2];
				array[index2] = temp;
				c++;
			}
			
		}

		printf("%d\n",c);
	}

	return 0;
}