#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, i;
  double d, w;
  cin >> n >> w;
  int a[2 * n];
  for (i = 0; i < 2 * n; i++) cin >> a[i];
  sort(a, a + 2 * n);
  d = min(a[n] * n * 1.5, 3.0 * a[0] * n);
  cout << fixed << showpoint;
  cout << setprecision(8);
  cout << min(d, 1.0 * w);
  return 0;
}
