#include <bits/stdc++.h>

using namespace std;

// X = 4x/3 [y = (x/3)]

// Y = min(7x/2, 7y/5)
//
// 1000X+2000Y=Z(maximalize)

//

double x, y;

double calc(double a)
{
  return (4 * a / 3 * 1000 + min(7 * (x - a) / 2, 7 * (y - a / 3) / 5) * 2000);
}

int main()
{
  cin >> x >> y;

  double low = 0, high = min(x, y * 3);
  for(int i = 0; i < 500; i++) {
    double l = (low * 2 + high) / 3;
    double r = (low + high * 2) / 3;
    if(calc(l) < calc(r)) low = l;
    else high = r;
  }
  cout << fixed << setprecision(10) << calc(low) << endl;
}