import java.util.HashSet val NAN = java.lang.Float.NaN data class A(val x: Float) fun box(): String { if (A(+0f) == A(-0f)) return "Fail: +0 == -0" if (A(+0f).hashCode() == A(-0f).hashCode()) return "Fail: hash(+0) == hash(-0)" if (A(NAN) != A(NAN)) return "Fail: NaN != NaN" if (A(NAN).hashCode() != A(NAN).hashCode()) return "Fail: hash(NaN) != hash(NaN)" val s = HashSet() for (times in 1..5) { s.add(A(3.14f)) s.add(A(+0f)) s.add(A(-0f)) s.add(A(-2.72f)) s.add(A(NAN)) } if (A(3.14f) !in s) return "Fail: 3.14 not found" if (A(+0f) !in s) return "Fail: +0 not found" if (A(-0f) !in s) return "Fail: -0 not found" if (A(-2.72f) !in s) return "Fail: -2.72 not found" if (A(NAN) !in s) return "Fail: NaN not found" return if (s.size == 5) "OK" else "Fail $s" }