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

struct node {
    int key;
    vector < int > kids;
};

vector < node > arr;

bool dfs(vector < node > &arr, int key, int pos)
{
    int parent = key;
    int leftchild, rightchild, leftpos, rightpos;
    leftchild = rightchild = leftpos = rightpos = -1;
    if (arr[pos].kids[0] != -1)
    {
        leftchild = arr[arr[pos].kids[0]].key;
        leftpos = arr[pos].kids[0];
    }

    if (arr[pos].kids[1] != -1)
    {
        rightchild = arr[arr[pos].kids[1]].key;
        rightpos = arr[pos].kids[1];
    }

    if (leftpos != -1 && rightpos != -1)
    {
        if (leftchild > parent || rightchild < parent)
        {
            return false;
        } else {
            return (dfs(arr, leftchild, leftpos) && dfs(arr, rightchild, rightpos));
        }
    } else if (leftpos == -1 && rightpos == -1)
    {
        return true;
    } else if (leftpos != -1 && rightpos == -1)
    {
        if (leftchild > parent)
        {
            return false;
        } else {
            return dfs(arr, leftchild, leftpos);
        }
    } else if (leftpos == -1 && rightpos != -1)
    {
        if (rightchild < parent)
        {
            return false;
        } else {
            return dfs(arr, rightchild, rightpos);
        }
    }
}

int main()
{
    ifstream fin("1.txt");
    ofstream fout("2.txt");

    int n;
    fin >> n;
    arr.resize(n);
    int key, num1, num2;
    if (n == 0)
    {
        cout << "YES";
    } else {
        for (int i = 0; i < n; i++)
        {
            fin >> key;
            fin >> num1 >> num2;
            arr[i].key = key;
            arr[i].kids.push_back(num1 - 1);
            arr[i].kids.push_back(num2 - 1);
        }

        if (dfs(arr, arr[0].key, 0))
        {
            cout << "YES";
        } else {
            cout << "NO";
        }
    }

}