CF126B.Password

Asterix, Obelix and their temporary buddies Suffix and Prefix has finally found the Harmony temple. However, its doors were firmly locked and even Obelix had no luck opening them.

A little later they found a string s, carved on a rock below the temple's gates. Asterix supposed that that's the password that opens the temple and read the string aloud. However, nothing happened. Then Asterix supposed that a password is some substring t of the string s.

Prefix supposed that the substring t is the beginning of the string s; Suffix supposed that the substring t should be the end of the string s; and Obelix supposed that t should be located somewhere inside the string s, that is, t is neither its beginning, nor its end.

Asterix chose the substring t so as to please all his companions. Besides, from all acceptable variants Asterix chose the longest one (as Asterix loves long strings). When Asterix read the substring t aloud, the temple doors opened.

You know the string s. Find the substring t or determine that such substring does not exist and all that's been written above is just a nice legend.

阿斯特里克斯、奥贝利克斯，以及他们暂时的伙伴后缀（Suffix）和前缀（Prefix），终于找到了和谐神庙。然而，神庙的大门被牢牢锁住，甚至连奥贝利克斯都未能将其打开。

稍后，他们在神庙大门下方的一块岩石上发现了一串字符串 $ s $。阿斯特里克斯猜测这便是开启神庙的密码，并将该字符串大声读出。然而，什么也没有发生。接着，阿斯特里克斯推测密码应为字符串 $ s $ 的某个子串 $ t $。

前缀（Prefix）认为子串 $ t $ 应当是字符串 $ s $ 的前缀；后缀（Suffix）认为子串 $ t $ 应当是字符串 $ s $ 的后缀；而奥贝利克斯则认为 $ t $ 应当出现在字符串 $ s $ 的内部，即 $ t $ 既不是 $ s $ 的前缀，也不是 $ s $ 的后缀。

阿斯特里克斯选择子串 $ t $ 时，力求满足所有同伴的要求。此外，在所有满足条件的候选子串中，阿斯特里克斯选择了最长的一个（因为阿斯特里克斯钟爱长字符串）。当他将子串 $ t $ 大声读出时，神庙的大门打开了。

已知字符串 $ s $，请找出满足上述条件的子串 $ t $；若不存在这样的子串，则判定前述全部描述仅是一个美好的传说。

You are given the string s whose length can vary from 1 to 106 (inclusive), consisting of small Latin letters.

给你一个字符串 $s$，其长度在 $1$ 到 $10^6$（含）之间，且仅由小写拉丁字母组成。

Print the string t. If a suitable t string does not exist, then print "Just a legend" without the quotes.

输出字符串 $t$。如果不存在合适的字符串 $t$，则输出 "Just a legend"（不带引号）。