#include<iostream> 

using namespace std;

 struct Node
 {
        int Data;
        Node* next;
 } *rear, *front;

void delQueue()
{
      Node *temp, *var=rear;
      if(var==rear)
      {
             rear = rear->next;
             delete var;
      }
      else
      cout << endl << "Queue is Empty";
}

void push(int value)
{
     Node *temp = new Node;
     temp->Data=value;
     if (front == NULL)
     {
           front=temp;
           front->next=NULL;
           rear=front;
     }
     else
     {
           front->next=temp;
           front=temp;
           front->next=NULL;
     }
}

void display()
{
     Node *var=rear;
     if(var!=NULL)
     {
           cout << endl << "Elements are:  ";
           while(var!=NULL)
           {
                cout << var->Data << " ";
                var=var->next;
           }
     cout << endl;
     } 
     else
     cout << "Queue is Empty";
}

int main()
{
     int i=0;
     front=NULL;
     cout << endl << " 1. Push to Queue";
     cout << endl << " 2. Pop from Queue";
     cout << endl << " 3. Display Data of Queue";
     cout << endl << " 4. Exit" << endl;
     while(1)
     {
          cout << endl << " Choose Option: ";
          cin >> i;
          
          switch(i)
          {
                case 1:
                {
                     int value;
                     cout << endl << "Enter a value to push into Queue: ";
                     cin >> value;
                     push(value); 
                     display();
                     break;
                }
                case 2:
                {
                     delQueue();
                     display();
                     break;
                }
                case 3:
                {
                     display();
                     break;
                }
                case 4:
                {
                     exit(0);
                }
                default:
                {
                     cout << "Wrong choice...";
                }
          }
     }
}