#include<iostream>
#include<iomanip>
using namespace std;
int main()
{
    string type;
    cin>> type;
    float liters , price;
    cin>> liters;
    cin>>price;
    if( type == "petrol" || type == "diesel")
    {
        if(liters >= 0 && price >=0)
        {
            cout<< fixed << setprecision(2) << liters * price;
        }
        else
        {
            cout<<"Invalid input";
        }
    }
    else
    {
        cout<<"Invalid input;"
    }
}