#include<iostream>
#include<algorithm>
#include<iomanip>

using namespace std;

int main()
{
	double c,d;cin>>c>>d;
	double x=(20*c-8*d)/13;
	double y=(21*d-7*c)/13;
	if(x<0)
	{
		x=0;
		y=7*d/5;
	}
	else if(y<0)
	{
		y=0;
		x=4*d;
	}
	cout<<fixed<<setprecision(6)<<x*1000+y*2000<<endl;
	return 0;
}