#include<bits/stdc++.h>
using namespace std;
int a,b,c; 
int main(){
   cin>>a>>b>>c;
   cout<<a*0.2+b*0.3+c*0.5; 
   return 0;
}

/**************************************************************
	Problem: 1565
	User: chenjingqi
	Language: C++
	Result: Accepted
	Time:39 ms
	Memory:2072 kb
****************************************************************/