fun main(args: Array<String>) {
    val k = readLine()!!.toInt()
    val (a,b) = readLine()!!.split(' ').map { s -> s.toInt() }
    var check = false
    for (num in a..b) {
        if (num % k == 0)
            check = true
    }
    println( if (check) "OK" else "NG" )
}