#include<bits/stdc++.h>
using namespace std;
int main(){
	float x,y,z,a,b,c,h;
	cin>>a>>b>>c;
	x=8.5*a;
	y=5.6*b;
	z=6.2*c;
	h=y+z+x*1.0;
	printf("%.1f",h);
}
/**************************************************************
	Problem: 1610
	User: tonghuatao
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/