#include<iostream>
using namespace std;
int A, B, C;
int main()
{
cin >> A >> B >> C;
cout << 0.2 * A + 0.3 * B + 0.5 * C;
return 0;
}
#include<iostream>
using namespace std;
int A, B, C;
int main()
{
cin >> A >> B >> C;
cout << 0.2 * A + 0.3 * B + 0.5 * C;
return 0;
}