Language: C

include<stdio.h>

#define MAX 2000000

int array,A[MAX+1];

void maxHeapify(int x){

  int l, r, t,max;

  l = 2 * x;

  r = 2 * x + 1;

  if ( l <= array && A[l] > A[x] )
    {
      max = l;
    }

  else max = x;

  if ( r <= array && A[r] > A[max] )
    {
      max = r;
    }
  if ( max != x )
    {
      t = A[x];
      A[x] = A[max];
      A[max] = t;

      maxHeapify(max);
    }
}

nt extract(){

  int num;

  if ( array < 1 ) return;

  num = A[1];

  A[1] = A[array--];

  maxHeapify(1);

  return num;

}


void increaseKey(int x, int key){

  int tmp;

if ( key < A[x] ) return;

  A[x] = key;

  while ( x > 1 && A[x/2] < A[x] ){

    tmp = A[x];
    A[x] = A[x/2];
    A[x/2] = tmp;

    x = x/2;
  }
}

void insert(int key){
  array++;
  A[array] = -1000000001;
  increaseKey(array, key);
}

int main(){

  int key;
  char moji[20];

  while(1){

    scanf("%s", moji);

    if ( moji[0] == 'i' )
      {
        scanf("%d", &key);

        insert(key);

      }
    else if ( strcmp(moji, "extract") == 0  )
      {
        printf("%d\n", extract());

      } else break;
  }
  return 0;
}

Compiler output:
main.c:1:8: error: expected '=', ',', ';', 'asm' or '__attribute__' before '<' token
    1 | include<stdio.h>
      |        ^
main.c: In function 'maxHeapify':
main.c:15:13: error: 'array' undeclared (first use in this function)
   15 |   if ( l <= array && A[l] > A[x] )
      |             ^~~~~
main.c:15:13: note: each undeclared identifier is reported only once for each function it appears in
main.c:15:22: error: 'A' undeclared (first use in this function)
   15 |   if ( l <= array && A[l] > A[x] )
      |                      ^
main.c: At top level:
main.c:36:1: error: unknown type name 'nt'; did you mean 'int'?
   36 | nt extract(){
      | ^~
      | int
main.c: In function 'extract':
main.c:40:8: error: 'array' undeclared (first use in this function)
   40 |   if ( array < 1 ) return;
      |        ^~~~~
main.c:40:20: error: 'return' with no value, in function returning non-void [-Wreturn-mismatch]
   40 |   if ( array < 1 ) return;
      |                    ^~~~~~
main.c:36:4: note: declared here
   36 | nt extract(){
      |    ^~~~~~~
main.c:42:9: error: 'A' undeclared (first use in this function)
   42 |   num = A[1];
      |         ^
main.c: In function 'increaseKey':
main.c:57:12: error: 'A' undeclared (first use in this function)
   57 | if ( key < A[x] ) return;
      |            ^
main.c: In function 'insert':
main.c:72:3: error: 'array' undeclared (first use in this function)
   72 |   array++;
      |   ^~~~~
main.c:73:3: error: 'A' undeclared (first use in this function)
   73 |   A[array] = -1000000001;
      |   ^
main.c: In function 'main':
main.c:84:5: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
   84 |     scanf("%s", moji);
      |     ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | include<stdio.h>
main.c:84:5: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
   84 |     scanf("%s", moji);
      |     ^~~~~
main.c:84:5: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:93:15: error: implicit declaration of function 'strcmp' [-Wimplicit-function-declaration]
   93 |     else if ( strcmp(moji, "extract") == 0  )
      |               ^~~~~~
main.c:1:1: note: include '<string.h>' or provide a declaration of 'strcmp'
  +++ |+#include <string.h>
    1 | include<stdio.h>
main.c:95:9: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
   95 |         printf("%d\n", extract());
      |         ^~~~~~
main.c:95:9: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:95:9: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:95:9: note: include '<stdio.h>' or provide a declaration of 'printf'