请问两个孩子（18岁和19岁）都是绿卡持有者，他们的父母其中一个是公民，他们要申请入籍需要各自申请N400吗？还是可以通过公民母亲直接从邮局办理护照？谢谢
-Was the parent got the US citizenship before the kids turned 18 years old? If yes, the kids do not need to file N-400, but file N-600 or directly apply for the US passport to claim their US citizenship. Otherwise, the kids need to file N-400, respectively.
