var log = ""

fun logged(value: String) =
    value.also { log += value }

object A {
    var x = ""
    var gets = ""
    var sets = ""

    operator fun get(vararg va: String): String {
        for (s in va) {
            gets += s
        }
        log += "get;"
        return x
    }

    operator fun set(vararg va: String, value: String) {
        for (s in va) {
            sets += s
        }
        log += "set;"
        x = value
    }
}

operator fun String.inc() = this + logged("inc;")

fun box(): String {
    A.x = "start;"
    val xx = A[logged("1;"), logged("2;"), logged("3;")]++
    if (xx != "start;") return "Failed xx: $xx"
    if (A.x != "start;inc;") return "Failed A.x: ${A.x}"
    if (A.gets != "1;2;3;") return "Failed A.gets: ${A.gets}"
    if (A.sets != "1;2;3;") return "Failed A.sets: ${A.sets}"
    if (log != "1;2;3;get;inc;set;") return "Failed log: $log"
    return "OK"
}