#include <bits/stdc++.h>
using namespace std;
int main(){
   float x,y,z,a;
   cin>>x>>y>>z;
   a=x*8.5+y*5.6+z*6.2;
   printf("%.1f",a);
}

/**************************************************************
	Problem: 1610
	User: huangluowei
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/