queue

struct node{
  int x;
  int y;
  int level;
};

node q[1000];
int front = 0;
int back = 0;

void init(){
  front = back = 0;
}

void push(int x, int y, int level){
  q[back].x = x;
  q[back].y = y;
  q[back].level = level;
  back++;
}

node pop(){
  return q[front++];
}

bool empty(){
   return (front == back);
}