#include<bits/stdc++.h>
using namespace std;
int main()
{
	float x,y,z;
	float n;
	cin>>x>>y>>z;
	n=x*8.5+y*5.6+z*6.2;
	printf("%.1f",n);
} 
/**************************************************************
	Problem: 1610
	User: tangkaixuan
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/