package foo

trait A
trait B : A
trait C : A
trait D : B, C
trait E : C

open class CB: B
class CB2: CB()

class CD: D

fun testPhrase(o: Any): String {
    var s = ""
    s += if(o is A) "Y" else "N"
    s += if(o is B) "Y" else "N"
    s += if(o is C) "Y" else "N"
    s += if(o is D) "Y" else "N"
    s += if(o is E) "Y" else "N"
    return s
}

fun box(): String {
    val b = CB()
    val b2 = CB2()
    val d = CD()
    val e = object : E {}

    if (testPhrase(b) != "YYNNN") return "bad b, it: ${testPhrase(b)}"
    if (testPhrase(b2) != "YYNNN") return "bad b2, it: ${testPhrase(b2)}"
    if (testPhrase(d) != "YYYYN") return "bad d, it: ${testPhrase(d)}"
    if (testPhrase(e) != "YNYNY") return "bad e, it: ${testPhrase(e)}"

    return "OK"
}