#include <iostream>
#include <vector>

using namespace std;

struct Node
{
    int key;
    int left;
    int right;
};

void traversal(Node* arr, vector <int> &values, int i)
{
    if (arr[i].left > 0)
    {
        traversal(arr, values, arr[i].left);
    }
    values.push_back(arr[i].key);
    if (arr[i].right > 0)
    {
        traversal(arr, values, arr[i].right);
    }
    return;
}

int main()
{
    ios_base::sync_with_stdio(false);
    freopen("height.in", "r", stdin);
    freopen("height.out", "w", stdout);
    int n, k, l, r;
    cin >> n;
    vector <int> values;
    Node arr[20];
    for (int i = 0; i < n; i++)
    {
        cin >> k >> l >> r;
        l--;
        r--;
        arr[i].key = k;
        arr[i].left = l;
        arr[i].right = r;
    }
    traversal(arr, values, 0);
    for (int i = 1; i < n; i++)
    {
        if (values[i - 1] >= values[i])
        {
            cout << "NO";
            return 0;
        }
    }
    cout << "YES";
    return 0;
}