#include<bits/stdc++.h>
using namespace std;
int main(){
	int x,y,i=0,s=0;
	float f;
	cin>>x>>y;
	i=x*2.5;
	s=y*1.5;
	f=i+s-1.5;
	printf("%.1lf",f);
}
/**************************************************************
	Problem: 1603
	User: huxuanchen
	Language: C++
	Result: Wrong Answer
****************************************************************/