#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, n, m, ar[200] = {0}, tp = 1;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    cin >> a >> b;
    for (int j = a + 1; j <= b; j++) {
      if (!ar[j]) tp++, ar[j]++;
    }
  }
  cout << ((tp == m + 1) ? "YES" : "NO") << endl;
  return 0;
}
