CTF-28解题思路

IyMjIOa6kOeggeWIhuaekO+8mgoKYGBgcGhwCjw/cGhwCmhpZ2hsaWdodF9maWxlKF9fRklMRV9fKTsgCmluY2x1ZGUoImZsYWcucGhwIik7IAovL2ZsYWcgaW4gY2xhc3MgZmxhZzsgCiRjdGZzaG93ID0gbmV3IGN0ZnNob3coKTsgCiR2MT0kX0dFVFsndjEnXTsgCiR2Mj0kX0dFVFsndjInXTsgCiR2Mz0kX0dFVFsndjMnXTsgCiR2MD1pc19udW1lcmljKCR2MSkgYW5kIGlzX251bWVyaWMoJHYyKSBhbmQgaXNfbnVtZXJpYygkdjMpOyAKaWYoJHYwKQp7CiAgICBpZighcHJlZ19tYXRjaCgiL1w7LyIsICR2MikpCiAgICB7CiAgICAgICAgaWYocHJlZ19tYXRjaCgiL1w7LyIsICR2MykpCiAgICAgICAgewogICAgICAgICAgICBldmFsKCIkdjIoJ2N0ZnNob3cnKSR2MyIpOwogICAgICAgIH0KICAgIH0KfQo/PgpgYGAKCiMjIyDogIPngrnvvJoKCioqcGhw5LitT1LkuI58fCBBTkTkuI4mJueahOWMuuWIq+aAu+e7kyoqCgrlj4LogIPotYTmlpnvvJrvvIhodHRwczovL3d3dy5qYjUxLm5ldC9hcnRpY2xlLzQyNDI1Lmh0be+8iQoKKirlm6DkuLrotYvlgLznmoTkvJjlhYjnuqc96auY5LqOYW5k5omA5LuldjDnmoTlgLzlj6/ku6XnlLF2MeadpeaOp+WItu+8jOaJgOS7peaIkeS7rOmcgOimgee7meWFtui1i+WAvOS4ujHkuZ/lsLHmmK90cnVlKioKCioq5Zug5Li6ZmxhZ+WcqOexu2N0ZnNob3fkuK3vvIzmiYDku6Xlj6/ku6Xnm7TmjqXlkb3ku6TmiafooYwqKgoKIyMgcGF5bG9hZO+8mgoKYGBgCj92MT0xJnYyPXZhcl9kdW1wKCRjdGZzaG93KSZ2Mz07CnYxPTEmdjI9c3lzdGVtKCJjYXQgZmxhZy5waHAiKS8qJnYzPSovOwpgYGAKCioq6L6T5YWlcGF5bG9hZOWQjuWPs+WHu+mhtemdouafpeeci+a6kOeggeWNs+WPr+eci+WIsGZsYWcqKg==