#include <bits/stdc++.h>
using namespace std;
int main(){
    double C,D;
    cin>>C>>D;
    double A,B;
    if(7*C/2<7*D/5){
        A=0;
        B=7*C/2;
    }else if(4*D<4*C/3){
        A=4*D;
        B=0;
    }else{
        A=20*C/13-8*D/13;
        B=-7*C/13+21*D/13;
    }
    printf("%.8f",1000*A+2000*B);
}