Erase and Extend (Easy Version)
This is the easy version of the problem. The only difference is the constraints on $$$n$$$ and $$$k$$$. You can make hacks only if all versions of the problem are solved.You have a string $$$s$$$, and you can do two types of operations on it:   Delete the last character of the string.  Duplicate the string: $$$s:=s+s$$$, where $$$+$$$ denotes concatenation. You can use each operation any number of times (possibly none).Your task is to find the lexicographically smallest string of length exactly $$$k$$$ that can be obtained by doing these operations on string $$$s$$$.A string $$$a$$$ is lexicographically smaller than a string $$$b$$$ if and only if one of the following holds:  $$$a$$$ is a prefix of $$$b$$$, but $$$a\ne b$$$;  In the first position where $$$a$$$ and $$$b$$$ differ, the string $$$a$$$ has a letter that appears earlier in the alphabet than the corresponding letter in $$$b$$$. 
In the first test, it is optimal to make one duplication: "dbcadabc" $$$\to$$$ "dbcadabcdbcadabc".In the second test it is optimal to delete the last $$$3$$$ characters, then duplicate the string $$$3$$$ times, then delete the last $$$3$$$ characters to make the string have length $$$k$$$."abcd" $$$\to$$$ "abc" $$$\to$$$ "ab" $$$\to$$$ "a" $$$\to$$$ "aa" $$$\to$$$ "aaaa" $$$\to$$$ "aaaaaaaa" $$$\to$$$ "aaaaaaa" $$$\to$$$ "aaaaaa" $$$\to$$$ "aaaaa".
The first line contains two integers $$$n$$$, $$$k$$$ ($$$1 \leq n, k \leq 5000$$$) — the length of the original string $$$s$$$ and the length of the desired string.The second line contains the string $$$s$$$, consisting of $$$n$$$ lowercase English letters.
Print the lexicographically smallest string of length $$$k$$$ that can be obtained by doing the operations on string $$$s$$$.
(n, k) = map(int, input().split())
s = input()
a = 'z' * k
for i in range(n):
    a = min(a, (s[:i + 1] * (k // (i + 1) + 1))[:k])
print(a)
(n, k) = map(int, input().split())
s = input()
print(min([(s[:i + 1] * (k // (i + 1) + 1))[:k] for i in range(n)]))
(n, k) = map(int, input().split())
s = input()
a = 'z' * k
for i in range(n):
    a = min(a, (s[:i + 1] * (k // (i + 1) + 1))[:k])
print(a)