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

using namespace std;

double c,d;

double f(double a)
{
	double ans=0.0,am;
	am=min(a*4/3,d*4);
	ans+=am*1000;
	ans+=min((c-am*3/4)*7/2,(d-am/4)*7/5)*2000;
	return ans;
}

int main()
{
	cin>>c>>d;
	
	double l=0.0,u=c;
	double m=0.0;
	double a,b;
	
	for(int i=0;i<100;i++)
	{
		a=f((l*2+u)/3);
		b=f((l+u*2)/3);
		if(a>b)
		{
			u=(l+u*2)/3;
			if(a>m)m=a;
		}
		else
		{
			l=(l*2+u)/3;
			if(b>m)m=b;
		}
	}
	
	cout<<fixed<<setprecision(6)<<m<<endl;
	return 0;
}