current_users = ['Niuniu', 'Niumei', 'GURR', 'LOLO']
new_users = ['GurR', 'Niu Ke Le', 'LoLo', 'Tuo Rui Chi']
upper_current_users = [x.upper() for x in current_users]
for user in new_users:
    if user.upper() in upper_current_users:
        print(f"The user name {user} has already been registered! Please change it and try again!")
    else:
        print(f"Congratulations, the user name {user} is available!")