s;
main(t){
	float c,d,a,b,x;
	scanf("%f%f",&c,&d);
	s=c*5<=d*2;
	t=c>=d*3;
	a=s?0:(t?d*4:(x=(c*15-d*6)/13)+x/3);
	b=s?c*3.5:(t?0:c-x+d-x/3);
	s=!printf("%f",a*1000+b*2000);
}