#include <bits/stdc++.h>
const int MAX = 1e6;
const int MOD = 1e9 + 7;
using namespace std;
int main() {
  int n;
  double w;
  cin >> n >> w;
  int cup[2 * (int)n];
  for (int i = 0; i < 2 * n; i++) scanf("%d", &cup[i]);
  sort(cup, cup + n * 2);
  int minb = cup[n];
  int ming = cup[0];
  double res = min(w, min(1.5 * n * cup[n], 3.0 * n * cup[0]));
  cout << setprecision(20) << res;
  return 0;
}
