#include <bits/stdc++.h>
using namespace std;
int main(int argc, char *argv[]) {
  int n, x, y, sum, max = 0;
  while (cin >> n, n) {
    for (int i = 0; i < n; i++) {
      cin >> x >> y;
      sum += x;
      if (y > max) {
        max = y;
      }
    }
    if (sum <= max) {
      cout << "yes" << endl;
    } else {
      cout << "no" << endl;
    }
  }
  return 0;
}
