#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<ll> t(m);
  vector<int> p(m);
  ll cur_t = 0;
  int cur_p = 0;
  rep(i, m)
  {
    cin >> t[i] >> p[i];
    if (abs(cur_t - t[i]) < abs(cur_p - p[i]))
    {
      cout << "No" << endl;
      return 0;
    }
    cur_t = t[i];
    cur_p = p[i];
  }
  cout << "Yes" << endl;
  return 0;
}