fun main() {
    val (n, m) = readLine()!!.split(" ").map{it.toInt()}
    var now: Long = 0
    var pos: Long = 0
    repeat(m){
        val (t, p) = readLine()!!.split(" ").map{it.toLong()}
        if(t-now < Math.abs(pos-p)){
            println("No")
            return
        }
        now = t
        pos = p
    }
    println("Yes")
}