#include<bits/stdc++.h>
using namespace std;
int main(){
	float a,b,c,i=0,x=0,z=0,h=0;
	cin>>a>>b>>c;
	i=a*8.5;
    x=b*5.6;
    z=c*6.2;
    h=i+x+z;
	printf("%.1lf",h);
} 
/**************************************************************
	Problem: 1610
	User: huxuanchen
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/