24 users have solved this problem:

admini, angus, lion, bear1212, dorian, henryho2, horiseun, programmer123, user, Ghetto, sheep, KarL06, Uasoni2, Conan, BurwoodChenFamily, dusky, Double_Slash, caterpillow, ja_kingy, awu, sandworm, amanda, newai, liangjeremy,