output_description: Print the string S after lowercasing the K-th character in it.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N K
      S
attempt: N, K = (i for i in input().split())
  K = int(K)
  X = list(N)
  if X[K - 1] == "A":
      X[K - 1] = "a"
  if X[K - 1] == "B":
      X[K - 1] = "b"
  if X[K - 1] == "C":
      X[K - 1] = "c"
  print("".join(X))
  
problem_description: Statement
  
  You are given a string S of length N consisting of `A`, `B` and `C`, and an
  integer K which is between 1 and N (inclusive). Print the string S after
  lowercasing the K-th character in it.
samples: [{"input": "3 1\n    ABC", "output": "aBC\n    \n\n* * *"}, {"input": "4 3\n    CABA", "output": "CAbA"}]