#include<iostream>
#include<exception>
using namespace std;
class ClassFullExpection : public expection{
    public:
    const char* what() const throw(){
        return "Error: Insufficient Slots";
    }
};
int main(){
    int slots, students;
    cin>>slots>> students;
    if(slots<0||students<0){
        cout<<"Invalid input"<<endl;
    }
    else{
        try{
            if(students>slots){throw
        classFullExpection();
        }
        cout<<"Enrollment successful"<<endl;
    }
    catch(classFullExceptions& e){
        cout <<e.what()<<endl;
    }
   }
   return 0;
}