#include<bits/stdc++.h>
using namespace std;
int main(){
	float x,y,z,j,h,g,w;
	cin>>x>>y>>z;
	j=x*8.5;
	h=y*5.6;
	g=z*6.2;
	w=j+h+g;
	printf("%.1f",w);
}
/**************************************************************
	Problem: 1610
	User: wangyiyang
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/