Language: C

include<stdio.h>
#include<stdlib.h>
#define NIL NULL

struct node{
  struct node *right;
  struct node *left;
  struct node *parent;
  int key;
};
typedef struct node * Node;

Node root;

void insert(int k){
  Node y = NIL;
  Node x = root;
  Node z;

  z = malloc(sizeof(struct node));
  z->key = k;
  z->left = NIL;
  z->right = NIL;

  while(x != NIL){
    y = x;
    if(z->key < x->key){
      x = x->left;
    }
    else{
      x = x->right;
    }
  }
  z->parent = y;
  if(y == NIL){
    root = z;
  }
  else if(z->key < y->key){
    y->left = z;
  }
  else{
    y->right = z;
  }
}

void inorder(Node u){
  if(u->left != NIL){
    inorder(u->left);
    printf(" %d", u->key);
    if(u->right != NIL){
      inorder(u->right);
    }
  }
  else{
    if(u->right != NIL){
      printf(" %d", u->key);
      inorder(u->right);
    }
    else{
      printf(" %d", u->key);
    }
  }
}


void preorder(Node u){
  printf(" %d", u->key);
  if(u->left != NIL){
    preorder(u->left);
    if(u->right != NIL){
      preorder(u->right);
    }
  }
  else{
    if(u->right != NIL){
      preorder(u->right);
    }
  }
}


int main(){
  int n, i, x;
  char com[20];
  scanf("%d", &n);

  for ( i = 0; i < n; i++ ){
    scanf("%s", com);
    if ( com[0] == 'i' ){
      scanf("%d", &x);
      insert(x);
    }
    else if ( com[0] == 'p' ){
      inorder(root);
      printf("\n");
      preorder(root);
      printf("\n");
    }
  }
  return 0;
}

Compiler output:
main.c:1:8: error: expected '=', ',', ';', 'asm' or '__attribute__' before '<' token
    1 | include<stdio.h>
      |        ^
In file included from main.c:2:
/usr/include/stdlib.h:98:8: error: unknown type name 'size_t'
   98 | extern size_t __ctype_get_mb_cur_max (void) __THROW __wur;
      |        ^~~~~~
/usr/include/stdlib.h:57:1: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
   56 | #include <bits/floatn.h>
  +++ |+#include <stddef.h>
   57 | 
/usr/include/stdlib.h:531:25: error: unknown type name 'size_t'
  531 |                         size_t __statelen) __THROW __nonnull ((2));
      |                         ^~~~~~
/usr/include/stdlib.h:531:25: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:561:25: error: unknown type name 'size_t'
  561 |                         size_t __statelen,
      |                         ^~~~~~
/usr/include/stdlib.h:561:25: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:661:42: error: unknown type name 'size_t'
  661 | extern void arc4random_buf (void *__buf, size_t __size)
      |                                          ^~~~~~
/usr/include/stdlib.h:661:42: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:672:22: error: unknown type name 'size_t'
  672 | extern void *malloc (size_t __size) __THROW __attribute_malloc__
      |                      ^~~~~~
/usr/include/stdlib.h:672:22: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:675:22: error: unknown type name 'size_t'
  675 | extern void *calloc (size_t __nmemb, size_t __size)
      |                      ^~~~~~
/usr/include/stdlib.h:675:22: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:675:38: error: unknown type name 'size_t'
  675 | extern void *calloc (size_t __nmemb, size_t __size)
      |                                      ^~~~~~
/usr/include/stdlib.h:675:38: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:683:36: error: unknown type name 'size_t'
  683 | extern void *realloc (void *__ptr, size_t __size)
      |                                    ^~~~~~
/usr/include/stdlib.h:683:36: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:695:41: error: unknown type name 'size_t'
  695 | extern void *reallocarray (void *__ptr, size_t __nmemb, size_t __size)
      |                                         ^~~~~~
/usr/include/stdlib.h:695:41: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:695:57: error: unknown type name 'size_t'
  695 | extern void *reallocarray (void *__ptr, size_t __nmemb, size_t __size)
      |                                                         ^~~~~~
/usr/include/stdlib.h:695:57: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:701:41: error: unknown type name 'size_t'
  701 | extern void *reallocarray (void *__ptr, size_t __nmemb, size_t __size)
      |                                         ^~~~~~
/usr/include/stdlib.h:701:41: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:701:57: error: unknown type name 'size_t'
  701 | extern void *reallocarray (void *__ptr, size_t __nmemb, size_t __size)
      |                                                         ^~~~~~
/usr/include/stdlib.h:701:57: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
In file included from /usr/include/stdlib.h:706:
/usr/include/alloca.h:32:22: error: unknown type name 'size_t'
   32 | extern void *alloca (size_t __size) __THROW;
      |                      ^~~~~~
/usr/include/alloca.h:25:1: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
   24 | #include <stddef.h>
  +++ |+#include <stddef.h>
   25 | 
/usr/include/stdlib.h:712:22: error: unknown type name 'size_t'
  712 | extern void *valloc (size_t __size) __THROW __attribute_malloc__
      |                      ^~~~~~
/usr/include/stdlib.h:712:22: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:718:45: error: unknown type name 'size_t'
  718 | extern int posix_memalign (void **__memptr, size_t __alignment, size_t __size)
      |                                             ^~~~~~
/usr/include/stdlib.h:718:45: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:718:65: error: unknown type name 'size_t'
  718 | extern int posix_memalign (void **__memptr, size_t __alignment, size_t __size)
      |                                                                 ^~~~~~
/usr/include/stdlib.h:718:65: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:724:29: error: unknown type name 'size_t'
  724 | extern void *aligned_alloc (size_t __alignment, size_t __size)
      |                             ^~~~~~
/usr/include/stdlib.h:724:29: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:724:49: error: unknown type name 'size_t'
  724 | extern void *aligned_alloc (size_t __alignment, size_t __size)
      |                                                 ^~~~~~
/usr/include/stdlib.h:724:49: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:961:23: error: unknown type name 'size_t'
  961 |                       size_t __nmemb, size_t __size, __compar_fn_t __compar)
      |                       ^~~~~~
/usr/include/stdlib.h:961:23: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:961:39: error: unknown type name 'size_t'
  961 |                       size_t __nmemb, size_t __size, __compar_fn_t __compar)
      |                                       ^~~~~~
/usr/include/stdlib.h:961:39: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:970:34: error: unknown type name 'size_t'
  970 | extern void qsort (void *__base, size_t __nmemb, size_t __size,
      |                                  ^~~~~~
/usr/include/stdlib.h:970:34: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:970:50: error: unknown type name 'size_t'
  970 | extern void qsort (void *__base, size_t __nmemb, size_t __size,
      |                                                  ^~~~~~
/usr/include/stdlib.h:970:50: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:1044:20: error: unknown type name 'size_t'
 1044 |                    size_t __len) __THROW __nonnull ((3, 4, 5));
      |                    ^~~~~~
/usr/include/stdlib.h:1044:20: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:1047:20: error: unknown type name 'size_t'
 1047 |                    size_t __len) __THROW __nonnull ((3, 4, 5));
      |                    ^~~~~~
/usr/include/stdlib.h:1047:20: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:1051:45: error: unknown type name 'size_t'
 1051 |                     char *__restrict __buf, size_t __len)
      |                                             ^~~~~~
/usr/include/stdlib.h:1051:45: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:1055:45: error: unknown type name 'size_t'
 1055 |                     char *__restrict __buf, size_t __len)
      |                                             ^~~~~~
/usr/include/stdlib.h:1055:45: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:1062:36: error: unknown type name 'size_t'
 1062 | extern int mblen (const char *__s, size_t __n) __THROW;
      |                                    ^~~~~~
/usr/include/stdlib.h:1062:36: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:1066:48: error: unknown type name 'size_t'
 1066 |                    const char *__restrict __s, size_t __n) __THROW;
      |                                                ^~~~~~
/usr/include/stdlib.h:1066:48: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:1073:8: error: unknown type name 'size_t'
 1073 | extern size_t mbstowcs (wchar_t *__restrict  __pwcs,
      |        ^~~~~~
/usr/include/stdlib.h:1073:8: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:1074:53: error: unknown type name 'size_t'
 1074 |                         const char *__restrict __s, size_t __n) __THROW
      |                                                     ^~~~~~
/usr/include/stdlib.h:1074:53: note: 'size_t' is defined in header '<stddef.h>'; this is probably fixable by adding '#include <stddef.h>'
/usr/include/stdlib.h:1077:8: error: unknown type name 'size_t'
 1077 | extern size_t wcstombs (char *__restrict __s,
      |        ^~~~~~
/usr/include/stdlib.h:1077:8: note: 'size_t' is defined in header '<stddef.h>'; this is probably