#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*(x-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;
	}
	
	printf("%.10lf\n", calc(low));
	return 0;
}