#include <iostream>
#include <vector>
#include <fstream>
using namespace std;

struct tree{
     int m;
     int LeftChild;
     int RightChild;
 };

    bool TreeorNot(vector<tree> &array, int node) {
    if (node < 0) {
        return true;
    } else {
        if ((node <= array[node].LeftChild) || (node >= array[node].RightChild)) {
            return false;
        } else {
            return (array, array[node].LeftChild)&&(array, array[node].RightChild);
        }

    }

}



int main() {
    ifstream cin("check.in");
    ofstream cout("check.out");
    int n;
    int node = 0;
    cin >> n;
    vector<tree> array(n);
    if (n == 0) {
        cout << "YES";
    } else {
        for (int i = 0; i < n; ++i) {
            cin >> array[i].m >> array[i].LeftChild >> array[i].RightChild;
            --array[i].LeftChild;
            --array[i].RightChild;
        }
    }
    if (TreeorNot(array, node)){
        cout << "YES";
    } else {
        cout << "NO";
    }
    cin.close();
    cout.close();
    return 0;
}