CF1029A.Many Equal Substrings

You are given a string $t$ consisting of $n$ lowercase Latin letters and an integer number $k$.

Let's define a substring of some string $s$ with indices from $l$ to $r$ as $s[l \dots r]$.

Your task is to construct such string $s$ of minimum possible length that there are exactly $k$ positions $i$ such that $s[i \dots i + n - 1] = t$. In other words, your task is to construct such string $s$ of minimum possible length that there are exactly $k$ substrings of $s$ equal to $t$.

It is guaranteed that the answer is always unique.

给你一个由 $n$ 个小写拉丁字母组成的字符串 $t$ 和一个整数 $k$。

我们定义字符串 $s$ 中从索引 $l$ 到 $r$ 的子串为 $s[l \dots r]$。

你的任务是构造一个长度尽可能小的字符串 $s$，使得恰好存在 $k$ 个位置 $i$ 满足 $s[i \dots i + n - 1] = t$。换言之，你的任务是构造一个长度尽可能小的字符串 $s$，使得 $s$ 中恰好有 $k$ 个等于 $t$ 的子串。

保证答案总是唯一的。

The first line of the input contains two integers $n$ and $k$ ($1 \le n, k \le 50$) — the length of the string $t$ and the number of substrings.

The second line of the input contains the string $t$ consisting of exactly $n$ lowercase Latin letters.

输入的第一行包含两个整数 $n$ 和 $k$（$1 \le n, k \le 50$）—— 分别表示字符串 $t$ 的长度和子串的数量。

输入的第二行包含字符串 $t$，该字符串恰好由 $n$ 个小写拉丁字母组成。

Print such string $s$ of minimum possible length that there are exactly $k$ substrings of $s$ equal to $t$.

It is guaranteed that the answer is always unique.

输出满足条件的最短字符串 $s$，使得 $s$ 中恰好有 $k$ 个子串等于 $t$。

保证答案唯一。