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<limits.h>

#define heapmax 500001

int heap[heapmax],heapsize;

void heapincreasekey(int [],int,int);

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 A[],int i){
  int largest,leftN,rightN,tmp;
  leftN=left(i);
  rightN=right(i);
  if(leftN<=heapsize && A[leftN]>A[i]){
    largest=leftN;
  }
  else {
    largest=i;
  }
  if(rightN<=heapsize && A[rightN]>A[largest]){
    largest=rightN;
  }
  if(largest!=i){
    tmp=A[largest];
    A[largest]=A[i];
    A[i]=tmp;
    maxheapify(A,largest);
  }
}

void Buildmaxheap(int A[]){
  int i;
  for(i=heapsize/2;i>=1;i--){
    maxheapify(A,i);
  }
}

void heapincreasekey(int A[], int i,int key){
  int tmp;
  A[i]=key;
  while(i>1 && A[parent(i)]<A[i]){
    tmp=A[i];
    A[i]=A[parent(i)];
    A[parent(i)]=tmp;
    i=parent(i);
  }
}

void maxheapinsert(int A[], int key){
  heapsize=heapsize+1;
  A[heapsize]=INT_MIN;
  heapincreasekey(A,heapsize,key);
}

int heapextractmax(int A[]){
  int max;
  max=A[1];
  A[1]=A[heapsize];
  heapsize=heapsize-1;
  maxheapify(A,1);
  return max;
}

int main(){
  int i=0,key;
  char M[2000000];
  
  while(1){
    scanf("%s",M);
    if(M[0]=='e'&&M[1]=='n'){
      break;
    }
    if(M[0]=='i'){
      scanf("%d",&key);
      maxheapinsert(heap,key);
    }
    if(M[0]=='e'&& M[1]=='x'){
      printf("%d\n",heapextractmax(heap));
    }
  }
  
  return 0;
}