#include<stdio.h>
int main(){
	
	float x,y,a,b,ans;
	scanf("%f%f",&x,&y);
	a=(2+3+5+7+11+13)/6.0;
	b=(4+6+8+9+10+12)/6.0;
	ans=a*x+b*y;
	printf("%f\n",ans);
	return 0;
}