using static System.Math;
using System;

public class Hello
{
    static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        var m = int.Parse(line[1]);
        getAns(m);
    }
    static void getAns ( int m)
    {
        var pret = 0L;
        var prep = 0;
        for (int i = 0; i < m; i++)
        {
            string[] line = Console.ReadLine().Trim().Split(' ');
            var t = long.Parse(line[0]);
            var p = int.Parse(line[1]);
            if (Abs(prep - p) > t - pret) { Console.WriteLine("No"); return; }
            pret = t;
            prep = p;
        }
        Console.WriteLine("Yes");
    }
}