#include<iostream>
#include<string>
using namespace std;
class customer{
    protected:
    stirng name;
    public:
    void display(){
        cin>>name;
        
    }
    
};
class meter{
    protected:
    int n;
    public:
    void display1(){
        cin>>n;
    }
};
class bill:public meter,public customer{
    public
    void res(){
        if(n<0){
            cout<<"Invalid input"<<endl;
            return 0;
        }
        int total=(n*5+50);
        cout<<total<<endl;
    }
};
int main)()
{
    bill b;
    b.display();b.display1();b.res();
    return 0;
}