#include <bits/stdc++.h>
using namespace std;
int main() {
  long int n, x, y, i, j;
  float sum1 = 0, sum2 = 0, mini, maxi, p, z;
  cin >> n >> x >> y;
  long int a[n];
  for (i = 0; i < n; i++) {
    cin >> a[i];
  }
  sort(a, a + n);
  mini = min(x, y);
  maxi = max(x, y);
  p = mini;
  j = 0;
  while (mini--) {
    sum1 = sum1 + a[n - 1 - j];
    j++;
  }
  z = maxi;
  while (maxi--) {
    sum2 = sum2 + a[n - 1 - j];
    j++;
  }
  cout << fixed << setprecision(8) << sum1 / p + sum2 / z;
}
