#include<stdio.h>
int main(){
	int c,d;
	double p,max;
	scanf("%d %d",&c,&d);
	if(3*d-c<0){
		max=4000.0*(double)d;
	}else{
		max=4000.0*(double)c/3.0+34000.0*(double)(3*d-c)/39.0;
		p=4000.0*(double)d-6000.0*(double)(3*d-c)/13.0;
		max=(max<p)?p:max;
	}
	printf("%f\n",max);
	return 0;
}