Problem:
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Priority Queue

A priority queue is a data structure which maintains a set $S$ of elements, each of with an associated value (key), and supports the following operations:

$insert(S, k)$: insert an element $k$ into the set $S$

$extractMax(S)$: remove and return the element of $S$ with the largest key

Write a program which performs the $insert(S, k)$ and $extractMax(S)$ operations to a priority queue $S$.
The priority queue manages a set of integers, which are also keys for the priority.

Input

Multiple operations to the priority queue $S$ are given. Each operation is given by "insert $k$", "extract" or "end" in a line. Here, $k$ represents an integer element to be inserted to the priority queue.

The input ends with "end" operation.

Output

For each "extract" operation, print the element extracted from the priority queue $S$ in a line.

Constraints

The number of operations $\leq 2,000,000$

$0 \leq k \leq 2,000,000,000$

Sample Input 1

insert 8
insert 2
extract
insert 10
extract
insert 11
extract
extract
end

Sample Output 1

8
10
11
2

Solution in C (judge verdict: Runtime Error)

#include<stdio.h>
#include<stdlib.h>
#include<limits.h>

#define SIZE 500000

int heap[SIZE];
int n=0;

int parent(int i){
  return i/2;
}

int left(int i){
  return 2*i;
}

int right(int i){
  return 2*i+1;
}

void maxHeapify(int i){
  int l = left(i),r = right(i);
  int largest,tmp;

  if(l <= n && heap[l] > heap[i]){
    largest = l;
  }else{
    largest = i;
  }

  if(r <= n && heap[r] > heap[largest]){
    largest = r;
  }

  if(largest != i){
    tmp = heap[i];
    heap[i] = heap[largest];
    heap[largest] = tmp;
    maxHeapify(largest);
  }
}

void buildMaxHeap(){
  int i;
  for(i = n/2; i > 0; i--){
    maxHeapify(i);
  }
}

void heapIncreaseKey(int i,int key){
  int tmp;

  heap[i] = key;

  while(i > 1 && heap[parent(i)] < heap[i]){
    tmp = heap[i];
    heap[i] = heap[parent(i)];
    heap[parent(i)] = tmp;
    i = parent(i);
  }
}

void maxHeapInsert(int key){
  n = n + 1;
  heap[n] = INT_MIN;
  heapIncreaseKey(n, key);
}

int heapExtractMax(){
  int max = heap[1];

  heap[1] = heap[n];
  n = n - 1;
  maxHeapify(1);

  return max;
}

int main(){
  int i,key;
  char com[2000000];

  for(i = 1; i <= 2000000; i++){
    scanf("%s",com);
    if(com[0] == 'i'){
      scanf("%d",&key);
      maxHeapInsert(key);
    }else if(com[0] == 'e' && com[1] == 'x'){
      printf("%d\n",heapExtractMax());
    }else if(com[0] == 'e' && com[1] == 'n'){
      break;
    }
  }

  return 0;
}