#include <iostream>
#include <iomanip>
using namespace std;
class QuantityCalculation{
    private:
    string name;
    float quan ,pricce;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;
    }
QuantityCalculator q;
q.quantity(name,quan,price);
q.quantity();
return 0;
}