#include<iostream>
#include<iomanip>
using namespace std;
class QuantityCalculation{
    private:
    string name;
    float quan,price;float res=0;
    public:
    void quantity(string name,float quan,float price ){
        res=quan*price;
    }
    void quantity(){
        cout<<fixed<<setprecision(2)<<res;
    }
};
int main()
{
    string name;
    float quan,price;
    cin >> name >> quan >> price;
    if(quan < 0||price<0||(name|="petrol"&&name|="diesel")){
        cout<<"Invalid input";
        return 0;
    }
QuantityCalculation q;
q.quantity(name,quan,price);
q.quantity();
return 0;
}