Consider the following queue operations. If two threads are executing in parallel, and the first thread executes the enqueue one or more times, and the second thread executes the dequeue one or more times, is the implementation correct? Why or why not? You may assume that each line of code executes atomically, and that each line executes in the order in which it is listed in the code.

1 public void enq (Item x) {
2 if (tail-head capacity)
3 throw new Exception();
4 tail++;
5 items (tail % capacity] X;
6 }
7 public Item deq () {
8 if (tail == head)
9 throw new Exception ();
10 head++;
11 Item item = items (head % capacity];
12 return item; 13 } }