#include<bits/stdc++.h>
using namespace std;
int main(){
	int a,b,c;
	cin>>a>>b>>c;
	cout<<a*0.2+b*0.3+c*0.5<<endl;
	
}
/**************************************************************
	Problem: 1565
	User: tangkaixuan
	Language: C++
	Result: Accepted
	Time:40 ms
	Memory:2072 kb
****************************************************************/