Dequeue in a Priority queue using a Sorted Dictionary in C# -

i have sorted dictionary of form:

sorteddictionary<prioritytype, list<t>> dictionary; 

where prioritytype enum class.

now trying make priority queue methods have apprehensions whether dequeue method work or not.

public t dequeue()     {         if (isempty())         {             throw new exception("the priority queue empty! dequeuing not possible!");         }          var highestprioritylist = dictionary[dictionary.keys.first()];         var topelement = highestprioritylist.firstordefault();         if (highestprioritylist.count == 0)         {             dictionary.remove(dictionary.keys.first());         }         highestprioritylist.removeat(0);         return topelement;     } 

please me improve method!

note: dequeue() method supposed remove , return object highest priority , before other elements same priority.

okay able modify above code suit dequeue operation!

public t dequeue()     {         var highestprioritylist = dictionary[dictionary.keys.first()];         if (highestprioritylist.count == 0)         {             dictionary.remove(dictionary.keys.first());         }         var topelement = highestprioritylist.first();         highestprioritylist.remove(topelement);         return topelement;     } 

now can dequeue long without invalidoperationexception caused missing element in list after removeat operation!