#include<bits/stdc++.h>
using namespace std;
int cnt;
typedef struct node{
	int data;
	node* left;
	node* right;
}*BiTree;

BiTree build(vector<string> v){
	BiTree root = new node;
	root->data = stoi(v[0]);
	root->left = nullptr;
	root->right = nullptr;
	
	queue<BiTree> q;
	q.push(root);
	int idx = 1;
	while(!q.empty()){
		BiTree curr = q.front();
		q.pop();
		if(idx < v.size()&&v[idx]!="null"){
			BiTree temp = new node;
			temp->data = stoi(v[idx]);
			temp->left = nullptr;
			temp->right = nullptr;
			
			curr->left = temp;
			q.push(curr->left);
		}
		idx++;
		if(idx < v.size()&&v[idx]!="null"){
			BiTree temp = new node;
			temp->data = stoi(v[idx]);
			temp->left = nullptr;
			temp->right = nullptr;
			
			curr->right = temp;
			q.push(curr->right);
		}
		idx++;
	}
	return root;
}

void dfs(BiTree root,int max_val){
	if(root == nullptr){
		return ;
	...