#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;
}



/**************************************************************
	Problem: 1565
	User: zhuangsongyu
	Language: C
	Result: Compile Error
****************************************************************/