import java.util.Scanner

import scala.collection.immutable.Range.Inclusive

object Problem274 {

  def proc(row: Int, col: Int, fromTo: Seq[(Int, Int)]): String = {

    val ranges: Seq[Inclusive] =
      fromTo flatMap { case (from, to) =>
        val oppositeFrom = col - 1 - to
        val oppositeTo = col - 1 - from
        Seq((from to to), (oppositeFrom to oppositeTo))
      }

    val isGoodWall =
      (0 until col / 2) forall { i =>
        val cnt = ranges count { range =>
          range.contains(i)
        }
        cnt <= 2
      }

    if (isGoodWall) "YES" else "NO"
  }

  def main(args: Array[String]) {
    val sc = new Scanner(System.in)
    val n = sc.nextInt()
    val m = sc.nextInt()
    val fromTo = Seq.fill(n)(sc.nextInt(), sc.nextInt())

    val result = proc(n, m, fromTo)
    println(result)
  }
}