简简单单

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