#include <bits/stdc++.h>
#define rep(i, ss, ee) for (int i = ss; i < ee; ++i)
using namespace std;

void solve() {
  int N, M, ta = 0, pa = 0, tb, pb;
  cin >> N >> M;
  rep(i, 0, M) {
    cin >> tb >> pb;
    if (abs(pa - pb) > ta - tb) {
      cout << "No" << endl;
      break;
    }
    ta = tb;
    pa = pb;
  }
  cout << "Yes" << endl;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  solve();
}