#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)
#define FOR(i,b,e) for (int i=(int)(b); i<(int)(e); i++)
#define ALL(x) (x).begin(), (x).end()

const double PI = acos(-1);

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  int n, m;
  cin >> n >> m;

  bool ck = true;
  long long cur = 0;
  int q = 0;
  REP (i, m) {
    long long t;
    int p;
    cin >> t >> p;
    if (abs(p - q) > t - cur)
      ck = false;
    cur = t;
    q = p;
  }

  if (ck)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  
  return 0;
}