#include<algorithm>
#include<numeric>
#include<iostream>
using namespace std;
long long n, m, k, A[100000];
int main() {
	cin >> n >> m >> k;
	for (int i = 0; i < n; i++) cin >> A[i];
	sort(A, A + n);
	cout << (100.0 * accumulate(A + max(0LL, n - m - k), A + n, 0LL) / accumulate(A, A + n, 0LL)) << endl;
	return 0;
}