#include<iostream>
#include<iomanip>
using namespace std;
class fuel
{
    public:
    virtual total(float q,float p)
    {
        cout<<fixed<<setprecision(2)<<q*p;
    }
};
int main()
{
    fuelcost obj;
    string s;
    cin>>s;
    float p,q;
    cin>>q>>p;
    if(s=="petrol" || s=="diesel" &&(q>e &&p>0))
    {
        obj.total(q,p)
    }
    else
    {
        cout<<"Invalid input";
    }
    return 0;
}