#include <bits/stdc++.h>

using namespace std;

double x, y;

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