text: struct node{
      int value;
      struct node *next;
  };
  
  struct queue{
      int size;
      struct node * head;
      struct node * tail;
  };
  
  // queue library
  void init_q(struct queue *);
  void add_q(struct queue *, int);
  int empty_q(struct queue *);
  int pop_q(struct queue *);
  
  
  
  
  