gistfile1.txt

int chec_balance (TreeNode* node) {
  if (node == NULL) {
    return 0;
  }
  
  int l = check_balance(node->left);
  int r = ...
  if (l == -1 || r== -1) {
    return -1;
  }
  
  if (abs(l-r) > 1) {
    return -1;
  } else {
    return max(l, r);
  }
}