بليز وين الخطأ في هذا البرنامج؟؟؟؟؟

بليز شوفولي شو الغلط عندي بالبرنامج هون ؟؟؟؟

#include <iostream> 
using namespace std; 


void readarray (int* Nptr, int n); 
void intersectionofintegerset(const int*Nptr1,int n, const int*Nptr2, int m); 


int main(){ 
const int arraysize=50; 
int n[arraysize]; 
int m[arraysize]; 
if( n[arraysize] <=arraysize ){ 
			return n[arraysize]; 
		return NULL; 
	}  
  cout<< " How many numbers would you like to enter in the first Set?\n"; 
   cin>> n[arraysize];  
   cout<< "Enter element 1\n"; 
   cin>> n[1]; 

	cout<< "Enter element 2\n"; 
	cin>> n[2]; 

	 cout<< "Enter element 3\n"; 
	 cin>> n[3]; 

	  cout<< " How many numbers would you like to enter in the second Set?\n"; 
	  cin>> m[arraysize]; 
	  cout<< "Enter element 1\n"; 
	  cin>> m[1]; 

	  cout<< "Enter element 2\n"; 
	  cin>> m[2]; 


   void readarray (int* Nptr, int n){ 
		 for(int i=0;i<=50;i++) 
		 cin>> n; 
		 } 
  void intersectionofintegerset(const int*Nptr1,int n, const int*Nptr2, int m){ 
	 cout<< "The elements of the first set is :\n"; 
	 cin>> n; 
	 cout<< "The element of the second set is :\n"; 
	 cin>> m; 


		  if(n==m) 
			cout<< cout<< "Intersection Of two Integer Set :"<< i; 

		  else 
			 cout<< "!!!!"; 
			 } 







	return 0; 
}