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

class ClassFullException{
};

   int main()
   {
       int availableSlots, studentsEnrolling;
       
       if(!(cin>>availableSlots>.studentsEnrolling))return 0;
       
       try
       {
           if(availableSlots , 0 || studentsEnrolling < 0)
           {
               cout <<"Invalid input"<<endl;
           }
           else if(studentsEnrolling > available Slots)
           {
               throw ClassFullException();
           }
           else {
               cout <<"Enrollment successfull"<<endl;
           }
       }
       catch(ClassFullException& e)
       {
           cout<<"Error: Insufficient Slots"<<endl;
       }
       return 0;
   }