#include <iostream>
#include <vector>
#include <algorithm>

struct node {
    int left;
    int right;
    int max;
    node * child_left;
    node * child_right;
};

node * build(int left, int right, std::vector<int> & a){

    node * res = new node;
    res->left = left;
    res->right = right;

    if (left == right){
        res->child_left = nullptr;
        res->child_right = nullptr;
        res->max = a[left];
    }   else {
        int mid = (left + right) / 2;
        res->child_left = build(left, mid, a);
        res->child_right = build(mid + 1, right, a);
        res->max = std::max(res->child_left->max, res->child_right->max);
    }

    return res;
}

int query(node * root, int left, int right){
    if (right < root->left || left > root->right){
        return -1;
    }
    if (left <= root->left && root->right <= right){
        return root->max;
    }
    int ans1 = query(root->child_left, left, right);
    int ans2 = query(root->child_right, left, right);
    return std::max(ans1, ans2);
}

void update(node * root, int i, int val){
    if (i < root->left || i > root->right){
        return;
    }
    if (root->left == root->right){
        root->max = val;
        return;
    }
    update(root->child_left, i, val);
    update(root->child_right, i, val);
    root->max = std::max(root->child_right->max, root->child_left->max);
}


int main() {
    int n = 100;
    std::vector<int> a(n + 1);
    for (int i = 1; i < n + 1; ++i){
        a[i] = i % 10;
    }
    node * root = build(1, n, a);
    std::cout<<query(root, 23, 35)<<std::endl;
    update(root, 29, 5);
    std::cout<<query(root, 23, 35)<<std::endl;
    update(root, 31, 100);
    std::cout<<query(root, 23, 35)<<std::endl;
    return 0;
}