#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: zhuangsongyu
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/