#include <bits/stdc++.h>
using namespace std;

int n, m, now = 0, nt = 0;

int main() {
  bool ch = 1;
  cin >> n >> m;
  for (int i = 0; i < n; ++i) {
    int t, p;
    cin >> t >> p;
    if (abs(p - now) > t - nt) ch = 0;
    nt = t, now = p;
  }
  if (ch)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}