#include<bits/stdc++.h>
using namespace std;
int main()
{
	float x,y,z,s;
	cin>>x>>y>>z;
    s=x*8.5+y*5.6+z*6.2;
    printf("%0.1f",s);
    return 0;
}
/**************************************************************
	Problem: 1610
	User: huanghao
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/