object Main {
  def main(args:Array[String]) = {
    val sc = new java.util.Scanner(System.in)
    val a = sc.nextInt //最初の整数が読み込まれる
    val c = sc.nextInt //2番目に出てきた整数が読み込まれる
    var a1 = 0
    var c1 = 0
    // val c = sc.nextInt //3番目に出てきた整数が読み込まれる
    if ((a + c) < 1 || (a + c) >= 100000) {
      println("out")
    }
    if ((a + c) > 0 && (a + c) <= 100000){
      a1 = a%2
      c1 = c%2
      if (a1 == c1){
        if (a1 == 1) {
          println("no")
        }
        if (a1 == 0) {
          println("ok")
        }
      }
      if (a1 != c1){
        println("ok")
      }
    }
  }
}
