Problem:
Score : 1300 points

Problem Statement

Takahashi has a string S of length N consisting of lowercase English letters.
On this string, he will perform the following operation K times:

Let T be the string obtained by reversing S, and U be the string obtained by concatenating S and T in this order.

Let S' be some contiguous substring of U with length N, and replace S with S'.

Among the strings that can be the string S after the K operations, find the lexicographically smallest possible one.

Constraints

1 \leq N \leq 5000

1 \leq K \leq 10^9

|S|=N

S consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

N K
S

Output

Print the lexicographically smallest possible string that can be the string S after the K operations.

Sample Input 1

5 1
bacba

Sample Output 1

aabca

When S=bacba, T=abcab, U=bacbaabcab, and the optimal choice of S' is S'=aabca.

Sample Input 2

10 2
bbaabbbaab

Sample Output 2

aaaabbaabb

Solution in PyPy3 (2.4.0) (judge verdict: Runtime Error)

U = ""
lines = input().split(" ")
N = int(lines[0])
K = int(lines[1])
S = input()
 
if N == 1 && K == 1:
  print(S)
else:
  T = S[::-1]
  
  for i in range(K):
    U += S
    U += T
 
  num = len(U) 
  arr = [U[j : (j+ N)] for j in range(num) if j + N <= num]        
  arr.sort()
 
  print(arr[0])