51 users have solved this problem:

he, Gomango999, iamnumber4, mohnishdeshpande, dumpy, quanlin, evanl, lion, bao3108, minhnhatnoe, binbau10, user, alexanyu, Edward, schua704, warren_huang, testcoder, henryho2, ndosh, davinformatics, programmer123, lupispuma74, horiseun, xiaoxiong, dorian, WenDidIAsk, loctildore, numb3r5, Philip_cpp, Matthewwww, Double_Slash, Sirhc_47, Lucas4732, pony_joe1, narsue, Vivek, OoogaDooga, awang, ralismark, dusky, Lithanium, sssss, wap, doantronganh2008, GMICE_89khoa, BuMiTa, freecoder_123, longphuctran, Nhom9, dungbetele, Supermarine_Spitfire