import scala.io.StdIn.readLine
import scala.util.matching.Regex

object RainSnow446 {
  def main(args:Array[String]): Unit ={
    def isNumContain(str:String) = str.matches("""[0-9]+""")
      
    val a = readLine()
    val b = readLine()
    if(isNumContain(a+b) && (a.toInt <= 12345) && (b.toInt <= 12345) && (a.toInt < b.toInt))
      println("OK")
    else
      println("NG")
  }
}