#include<bits/stdc++.h> 
using namespace std;
float n,q,s,p;
int main(){
     cin>>n>>q>>s;
     p=n*8.5+q*5.6+s*6.2;
     printf("%.1f",p);
}
/**************************************************************
	Problem: 1610
	User: chenyichuen
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/