#include <bits/stdc++.h>
using namespace std;
int main(){
	int x,y;
	float d;
	cin>>x>>y;
	d=x*2.5+y*1.5-2.5;
	printf("%.1f",d);
    }
/**************************************************************
	Problem: 1603
	User: tonghuawei
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/