heap

int heap[MAX_N],sz = 0;
void push(int x){
  int  i = sz++;
  while(i>0){
    int p = (i-1)/2;
    if(heap[p] <= x)break;
    heap[i] = heap[p];
    i=p;
  }
  
  heap[i] = x;
}

int pop(){
  int ret = heap[0];
  int x = heap[--sz];
  int i=0;
  while(i*2+1<sz){
    int a= i*2 + 1,b= i*2 +2;
    if(b<sz && heap[b] < heap[a]) a= b;
    
    if(heap[a] >=x)break;
    heap[i] = heap[a];
    i=a;
  }
  
  heap[i] =x;
  return ret;
}