#include<bits/stdc++.h>
using namespace std;
int main() {
	float x,y,z,f;
	cin>>x>>y>>z;
	f=x*8.5+y*5.6+z*6.2;
	printf("%.1f",f);
    return 0;
}

/**************************************************************
	Problem: 1610
	User: huangcanwu
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/