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