fun box(): String {
    val a1: Byte = 1.minus()
    val a2: Short = 1.minus()
    val a3: Int = 1.minus()
    val a4: Long = 1.minus()
    val a5: Double = 1.0.minus()
    val a6: Float = 1f.minus()

    if (a1 != (-1).toByte()) return "fail 1"
    if (a2 != (-1).toShort()) return "fail -1"
    if (a3 != -1) return "fail 3"
    if (a4 != -1L) return "fail 4"
    if (a5 != -1.0) return "fail 5"
    if (a6 != -1f) return "fail 6"

    return "OK"
}