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

const int leftkey=-1000000001;
const int rightkey=1000000001;

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

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



}



int main() {
//    ifstream cin("check.in");
//    ofstream cout("check.out");
    int n;
    cin >> n;
    vector<tree> array(n);
    if (n == 0) {
        cout << "YES";
//        cin.close();
//        cout.close();
        return 0;
    } 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, 1, leftkey, rightkey)){
            cout << "YES";
        } else {
            cout << "NO";
        }
    }

//    cin.close();
//    cout.close();
    return 0;
}