// editor1
#include <iostream>
#include<iomanip>
#include<string>
using namespace std;
class qty{
    public:
    float quan,price;
    float res=0;
    void qtyy(float quan, float price,string name){
        if (name ="petrol" || name="diesel"){
        if (quan<=0 || price<=0){
        cout<<"Invalid input";
    }
        res=quan*price;
         cout<<fixed<<setprecision(2)<<res;
        }
        else{
            cout<<"Invalid input";
        }
    }
       
};
int main(){
    string name;
    float quan, price;
    cin>>name;
    
    cin>>quan>>price;
   
    qty q;
    q.qtyy(quan,price,name);
    return 0;
}