#include<bits/stdc++.h>
using namespace std;
int main(){
	int x,y,i=0,s=0;
	float a;
	cin>>x>>y;
	i=x*2.5;
	s=y*1.5;
	a=i+s-2.5;
	printf("%.1lf",a);
}

/**************************************************************
	Problem: 1603
	User: huxuanchen
	Language: C++
	Result: Wrong Answer
****************************************************************/