c6c

#include <cmath>
#include <string>
#include <utility>
#include <iostream>
#include <algorithm>

struct Node {
    char color;
    int key;
    struct Node *left;
    struct Node *right;
    struct Node *parent;
};

std::pair<bool, int> chk(Node *n) {
    if (n == nullptr) {
        return {true, 1};
    }
    if ((n->left && (n->left->key >= n->key)) || (n->right && (n->right->key <= n->key))) {
        return {false, -1};
    }
    int cnt;
    if (n->color == 'R') {
        cnt = 0;
        if ((n->left && n->left->color == 'R') || (n->right && n->right->color == 'R')) {
            return {false, -1};
        }
    } else {
        cnt = 1;
    }
    std::pair<bool, int> pr = chk(n->right);
    std::pair<bool, int> pl = chk(n->left);
    return {pr.first && pl.first && (pr.second == pl.second), pr.second + cnt};
}

bool isBalanced(Node *n) {
    if (n->color == 'R') {
        return false;
    }
    return chk(n).first;
}

int main() {
    int n = 0, root_num = 0;
    std::cin >> n;
    if (n == 0) {
        std::cout << "NO\n";
        exit(0);
    }
    std::cin >> root_num;
    auto nodes = new Node *[n + 1];
    for (int i = 1; i < n + 1; ++i) {
        nodes[i] = new Node;
    }
    int number;
    std::string left, right;
    for (int i = 1; i <= n; ++i) {
        std::cin >> number >> nodes[number]->key >> left >> right >> nodes[number]->color;
        if (left != "null") {
            nodes[number]->left = nodes[std::stoi(left)];
            nodes[std::stoi(left)]->parent = nodes[number];
        } else {
            nodes[number]->left = nullptr;
        }
        if (right != "null") {
            nodes[number]->right = nodes[std::stoi(right)];
            nodes[std::stoi(right)]->parent = nodes[number];
        } else {
            nodes[number]->right = nullptr;
        }
    }
    if (isBalanced(nodes[root_num])) {
        std::cout << "YES\n";
    } else {
        std::cout << "NO\n";
    }
    for (int i = 1; i < n + 1; ++i) {
        delete nodes[i];
    }
    delete[] nodes;
    return 0;
}