#include<iostream>
#include<iomanip>
using namespace std;
int main(){
    string membershiptype;
    int discountstatus;
    float duration;
    cin>>memebershiptype>>discountstatus>>duration;
    
    if(duration<0||(discountstatus!=0 &&discountstatus!=1)){
        cout<<"invalid input";
        return 0;
    }
    float costpermonth;
    if(membershiptype=="basic"){
        costpermonth=30.0;
    }
    else if(membershiptype=="standard"){
        costpermonth=50.0;
    }
    else if(membershiptype=="premium"){
        costpermonth=80.0;
    }
    else{
        cout<<"invalid input";
        return 0;
    }
    
    float totalcost=costpermonth*duration
    if(discountstatus==1){
        totalcost*=0.8;
        cout<<fixed<<setprecision(2)<<totalcost;
        return 0;
    }
}