#include<bits/stdc++.h>
using namespace std;
int main(){
    int x,y;
    float z;
    cin>>x>>y;
    z=x*2.5+y*1.5-2.5;
    printf("%.1f",z);
}
/**************************************************************
	Problem: 1603
	User: lijinkai
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/