def checkPasswd(password):
    # 密码长度要求
    if len(password)<=8:
        return "NG"
    # 至少包含三种
    a,b,c,d=0,0,0,0 # 是否存在
    for char in password:
        if ord("a")<=ord(char)<=ord("z"):
            a=1
        elif ord("A")<=ord(char)<=ord("Z"):
            b=1
        elif ord("0")<=ord(char)<=ord("9"):
            c=1
        else:
            d=1
    if a+b+c+d<3:
        return "NG"
    # 重复的长度大于2的子串
    for i in range(len(password)-3):
        slice_=password.split(password[i:i+3])
        if len(slice_)>=3:
            return "NG"
    return "OK"

import sys
if __name__=="__main__":
    for password in sys.stdin:
        print(checkPasswd(password.strip()))