#include <iostream>
#include <vector>
#include <fstream>

using namespace std;

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

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

bool correct(int num,vector<tree>*tree,int lkey,int rkey) {
    bool leftsubtree=true;
    bool rightsubtree = true;
    if ((*tree)[num].key <= lkey || (*tree)[num].key >= rkey) {
        return false;
    }
    else {
        if ((*tree)[num].left != 0) {
            leftsubtree = correct((*tree)[num].left, tree, lkey, (*tree)[num].key);
        }
        if ((*tree)[num].right != 0) {
            rightsubtree = correct((*tree)[num].right, tree, (*tree)[num].key, rkey);
        }
        return leftsubtree & rightsubtree;
    }
}

int main() {
    ifstream fin("check.in");
    ofstream fout("check.out");
    int n;
    fin >> n;
    vector<tree> ttree;
    tree treelevel;
    ttree.push_back(treelevel);
    for (int i = 0; i < n; i++) {
        fin >> treelevel.key >> treelevel.left >> treelevel.right;
        ttree.push_back(treelevel);
    }
    if (n != 0) {
        if (correct(1, &ttree, leftkey, rightkey)) {
            fout << "YES";
        } else {
            fout << "NO";
        }
    }
    else {
        fout << "YES";
    }
    return 0;

}