#include <cstdio>

#include <vector>

using namespace std;

int main() {
	for (;!feof(stdin);) {
		int count;
		if (scanf("%d", &count) != 1)
			break;

		std::vector<int> monsters, locs;
		monsters.resize(count);
		locs.resize(count);

		for (int i = 0; i < count; i++) {
			scanf("%d", &monsters[i]);
			monsters[i]--;
			locs[monsters[i]] = i;
		}

		int steps=0;
		for (int i = 0; i < count; i++) {
			if (monsters[i] != i) {
				int m1 = monsters[i];
				monsters[i] = i;
				monsters[locs[i]] = m1;
				locs[m1] = locs[i];
				locs[i] = i;
				steps++;
			}
		}
		printf("%d\n", steps);
	}

	return 0;
}