output_description: Print the lexicographically smallest possible string that can be the string S
  after the K operations.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N K
      S
attempt: # coding:utf-8
  tp = input().split()
  N = int(tp[0])
  K = int(tp[1])
  S = input()
  Sd = ""
  for i in range(K):
      T = S[::-1]
      U = S + T
      rtp = []
      for h in range(K):
          rtp.append(U[h : h + N])
      rtp.sort()
      Sd = rtp[0]
      S = Sd
  print(Sd)
  
problem_description: 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.
samples: [{"input": "5 1\n    bacba", "output": "aabca\n    \n\nWhen S=`bacba`, T=`abcab`, U=`bacbaabcab`, and the optimal choice of S' is\nS'=`aabca`.\n\n* * *"}, {"input": "10 2\n    bbaabbbaab", "output": "aaaabbaabb"}]