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 <string.h>
#define NIL -2000000001
#define MAX 500000
#define DELETED -1

int S[MAX];

int main(void){
  int i, k;
  char order[10];
  int largest = 0;
  int largestindex = 0;
  int end = 0;

  for(i = 0 ; i < MAX; i++)
    S[i] = NIL;

  while(1){

    scanf("%s", order);
    if(strcmp(order, "end") == 0)break;

    if(strcmp(order, "insert") == 0){
      scanf("%d", &k);
      S[end] = k;
    end++;
    }

    if(strcmp(order, "extract") == 0){
      largest = 0;
      for(i = 0; i < end; i++){
        if(S[i] > largest){
          largest = S[i];
          largestindex = i;
        }
      }
      printf("%d\n", largest);
      S[largestindex] = DELETED;
    }
  }

  return 0;
}