/* -*- coding: utf-8 -*-
 *
 * 1205.cc:  No.1205 Eye Drops - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_M = 100000;

/* typedef */

typedef long long ll;

/* global variables */

/* subroutines */

/* main */

int main() {
  int n, m;
  scanf("%d%d", &n, &m);

  ll t = 0;
  int p = 0;
  for (int i = 0; i < m; i++) {
    ll ti;
    int pi;
    scanf("%lld%d", &ti, &pi);

    if (ti - t < abs(p - pi)) {
      puts("No");
      return 0;
    }

    t = ti, p = pi;
  }

  puts("Yes");
  return 0;
}