这段程序会输出什么？

final class Box {
    var count: Int
    init(count: Int) { self.count = count }
}

struct Packet {
    var label: String
    var box: Box
}

var first = Packet(label: "A", box: Box(count: 1))
var second = first
second.label = "B"
second.box.count += 1

print(first.label, second.label)
print(first.box.count, second.box.count)