#include<iostream>
#include <exception>
using namespace std;

class ClassFullException : public exception{
    public:
    const  chart* what() const noexcept override{
        return "Error :Insufficient slots";
    }
};

int main(){
    int slots,students;
    cin>> slots>> students;
    
    if (slots< 0|| students <0){
        cout <<"Invalid input";
        return 0";
    }
    try {
        if(students > slots)
        throw 
        ClassFullexception();
        cout<<"Enrollment successful";
    }
    catch(ClassFullException& e){
        cout << e.what()
    }
    return 0;
}