#include<bits/stdc++.h>
using namespace std;
int main(){
	int i,n;
	float z=0,x=0,y=0;
	cin>>i>>n;
	x=i*2.5;
	y=n*1.5;
	z=x+y-2.5;
	printf("%.1f",z);
}
/**************************************************************
	Problem: 1603
	User: huxuanchen
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/