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

int main() {
  int n, m;
  cin >> n >> m;
  int x = 0, y = 0;
  for (int i = 0; i < m; i++) {
    int t, p;
    cin >> t >> p;
    if (abs(p - y) > t - x) {
      cout << "No" << endl;
      return 0;
    }
    x = t;
    y = p;
  }
  cout << "Yes" << endl;
  return 0;
}