#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;

int main(void)
{
  int n, m;
  cin >> n >> m;
  vector<int> t(m);
  vector<ll> p(m);
  bool pos = true;
  rep(i, m - 1)
  {
    cin >> t[i] >> p[i];
    if (abs(p[i + 1] - p[i]) > abs(t[i + 1] - t[i]))
    {
      pos = false;
    }
  }
  if (pos)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}