print("queue data structure")
queue=[]
while True:
    print("what function do you want to perform? \n 1.insert an element,2.remove an element,3.check the size of a stach,4.emptiness of stack.5.exit")
    n = int(input())
    if n== 1:
        print("enter the element you want to insert:")
        l = input()
        queue.append(l)
        print("elements in queue are:",queue)
    elif n == 2:
        if queue==[]:
            print("empty queue.you cannot delete!!")
        else:
            queue.pop(0)
            print("elements in stack are :",queue)
    elif n==3:
        print("size of queue is:",len(queue))
    elif n==4:
        if queue==[]:
            print("your queue is empty!!")
        else:
            print("you have",len(queue),"elements in your queue")
    elif n==5:
            print("exit")
            break
                  
            
