#include <iostream>
#include <map>

using namespace std;

//ios::sync_with_stdio(false);

int main()
{
    unsigned n = 0;

	while (cin >> n) {
		if (n == 0) {
			cout << 0 << endl;
			continue;
		}
		unsigned cages[n];
		for (unsigned i=0; i<n; ++i) {
			cin >> cages[i];
		}

		unsigned long steps = 0;

		
		for (unsigned j=n-1; j>0; --j) {
			
			while ( cages[j] != j+1) {
				int tmp = cages[j];
				cages[j] = cages[tmp-1];
				cages[tmp-1] = tmp;
				++steps;

				//cout << " -- " << j << " " << cages[j] << endl;
			}
		}

		cout << steps << endl;
	}
}