Problem Statement

You are given $N$ strings $S_1,\ldots,S_N$.

For a sequence $(A_1,\ldots,A_K)$ of length $K$ where all elements are between $1$ and $N$, inclusive, define the string $f(A_1,\ldots,A_K)$ as $S_{A_1}+S_{A_2}+\dots+S_{A_K}$. Here, + represents string concatenation.

Among all $f(A_1,\dots,A_K)$ for the $N^K$ sequences, find the lexicographically smallest string.

Constraints

• $1\leq N \leq 10^5$
• $1\leq K \leq 10^5$
• $S_i$ is a string consisting of lowercase English letters with length at most $10$.
• $N$ and $K$ are integers.

Input

The input is given from Standard Input in the following format:

N K
S_1
\vdots
S_N

Output

Output the answer.