text: 
  #include "pch.h"
  using namespace std;
  
  int run(TreeNode *root) {
  	if (root == NULL)
  		return 0;
  	int left = run(root->left);
  	int right = run(root->right);
  	if (left == 0 || right == 0)
  		return left + right + 1;
  	return min(left, right) + 1;
  }