func blockable(str) {
    var blocks = [
        "BO", "XK", "DQ", "CP", "NA", "GT", "RE", "TG", "QD", "FS",
        "JW", "HU", "VI", "AN", "OB", "ER", "FS", "LY", "PC", "ZM" ]

    var strUp = str.Upper()
    var fin = ""

    for c in strUp {
        for j in blocks.Indices() {
            if blocks[j].StartsWith(c) || blocks[j].EndsWith(c) {
                fin += c
                blocks[j] = ""
                break
            }
        }
    }

    return fin == strUp
}

func canOrNot(can) => can ? "can" : "cannot"

for str in [ "A", "BARK", "BooK", "TrEaT", "comMON", "sQuAd", "Confuse" ] {
    print("\"\(str)\" \(canOrNot(blockable(str))) be spelled with blocks.")
}