while True:
    try:
        s = input()
        if len(s) > 8:
            zmd = 0
            zmx = 0
            sz = 0
            ts = 0
            for i in s:
                if i.isupper():
                    zmd = 1
                elif i.islower():
                    zmx = 1
                elif i.isdigit():
                    sz = 1
                else:
                    ts = 1
            if (zmd + zmx + sz + ts) >= 3:
                # 判断子串是否有重复,否OK 是 NG
                n = len(s)
                cnt_all = []
                for i in range(0, n - 2):
                    for j in range(i + 3, n):
                        cnt_all.append(s.count(s[i:j]))    
                max_n = max(cnt_all)
                if max_n >= 2:
                    print('NG')
                else:
                    print('OK')
            else:
                print('NG')
        else:
            print('NG')
    except:
        break