{"raw_statement":[{"iden":"problem statement","content":"You are given a string $s$. Among the **different** substrings of $s$, print the $K$\\-th lexicographically smallest one.\nA substring of $s$ is a string obtained by taking out a non-empty contiguous part in $s$. For example, if $s$ $=$ `ababc`, `a`, `bab` and `ababc` are substrings of $s$, while `ac`, `z` and an empty string are not. Also, we say that substrings are different when they are different as strings.\nLet $X = x_{1}x_{2}...x_{n}$ and $Y = y_{1}y_{2}...y_{m}$ be two distinct strings. $X$ is lexicographically larger than $Y$ if and only if $Y$ is a prefix of $X$ or $x_{j} > y_{j}$ where $j$ is the smallest integer such that $x_{j} \\neq y_{j}$."},{"iden":"constraints","content":"*   $1$ $≤$ $|s|$ $≤$ $5000$\n*   $s$ consists of lowercase English letters.\n*   $1$ $≤$ $K$ $≤$ $5$\n*   $s$ has at least $K$ different substrings."},{"iden":"partial score","content":"*   $200$ points will be awarded as a partial score for passing the test set satisfying $|s|$ $≤$ $50$."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$s$\n$K$"},{"iden":"sample input 1","content":"aba\n4"},{"iden":"sample output 1","content":"b\n\n$s$ has five substrings: `a`, `b`, `ab`, `ba` and `aba`. Among them, we should print the fourth smallest one, `b`. Note that we do not count `a` twice."},{"iden":"sample input 2","content":"atcoderandatcodeer\n5"},{"iden":"sample output 2","content":"andat"},{"iden":"sample input 3","content":"z\n1"},{"iden":"sample output 3","content":"z"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}