#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: huanglingkai
	Language: C++
	Result: Accepted
	Time:25 ms
	Memory:2072 kb
****************************************************************/