#include<iostream>

using namespace std;

struct Node{
    int key, l, r;
};

Node a[200001];

bool check(Node root)
{
    if ((root.key > a[root.r].key) && (root.r > 0))
        return false;
    if ((root.key < a[root.l].key) && (root.l > 0))
        return false;
    if (root.l > 0)
        check(a[root.l]);
    if (root.r > 0)
        check(a[root.r]);
    return true;
}
int le, ri;
int main()
{
    freopen("check.in", "r", stdin);
    freopen("check.out", "w", stdout);
    int n, key, l, r;
    cin >> n;
    for (int i = 1; i <= n; i++)
        cin >> a[i].key >> a[i].l >> a[i].r;
    if (check(a[1])== true)
        cout << "YES";
    else
        cout << "NO";
    return 0;
}
/*
6
-2 0 2
8 4 3
9 0 0
3 5 6
0 0 0
6 0 0
*/
/*
0
*/
/*
3
5 2 3
6 0 0
4 0 0
*/