#include <bits/stdc++.h>
using ll = long long;
using llu = long long unsigned;

using namespace std;

int main() {
    int N;
    cin >> N;
    int score[101] = {};
    for (int i=0; i<N; i++) {
        int a, b;
        cin >> a >> b;
        score[b]+=a;
    }
    string result = "YES";
    for (int i=1; i<=N; i++) {
        if (score[0] < score[i]) { result = "NO"; }
    }
    cout << result << endl;
    return 0;
}