#include <bits/stdc++.h>
using namespace std;
typedef struct Node {
    char data;
    struct Node* left;struct Node* right;
}*STree;

string ques_pre="";
string ques_in="";
string ans_pre="";
string ans_in="";
void pre(STree root,string &v) {
    if (root==NULL) {
        return;
    }
    v.push_back(root->data);
    pre(root->left,v);
    pre(root->right,v);
}

void in(STree root,string &v) {
    if (root==NULL) {
        return;
    }
    in(root->left,v);
    v.push_back(root->data);
    in(root->right,v);
}

void buildSTree(STree &root,char data) {
    if (root==NULL) {
        root =new Node;
        root->data = data;
        root->left = NULL;
        root->right = NULL;
        return;
    }
    if (data==root->data) {
        return;
    }
    if (data<root->data) {
        buildSTree(root->left,data);
    }
    if (data>root->data) {
        buildSTree(root->ri...