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