#include<bits/stdc++.h>
using namespace std;
int main(){
    float x,y,z;
    cin>>x>>y>>z;
    printf("%.1f",x*8.5+y*5.6+z*6.2);
	
	
}
/**************************************************************
	Problem: 1610
	User: lvrenxiang
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/