#include<bits/stdc++.h>
using namespace std;
int main(){
	int x,y,z;
	float A;
	cin>>x>>y>>z;
	A=x*0.2+y*0.3+z*0.5;
	cout<<A;
}
/**************************************************************
	Problem: 1565
	User: zengyixuan
	Language: C++
	Result: Accepted
	Time:46 ms
	Memory:2072 kb
****************************************************************/