fun main(args: Array<String>) {
    val k = readLine()!!.toInt()
    val (a, b) = readLine()!!.split(" ").map{ it.toInt() }
    
    var f = false

    for(i in a .. b){
        if(i % k == 0) f = true
    }

    println(if(f) "OK" else "NG")

}