#include<bits/stdc++.h>
using namespace std;
int main(){
	float x=8.5,y=5.6,z=6.2,h,a,b,c;
	cin>>a>>b>>c;
	h=(x*a+y*b+z*c)*1.0;
	printf("%.1f",h);
	return 0;
}
/**************************************************************
	Problem: 1610
	User: toughuatao
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/