Problem:
Score : 100 points

Problem 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.

Constraints

1 ≤ N ≤ 50

1 ≤ K ≤ N

S is a string of length N consisting of A, B and C.

Input

Input is given from Standard Input in the following format:

N K
S

Output

Print the string S after lowercasing the K-th character in it.

Sample Input 1

3 1
ABC

Sample Output 1

aBC

Sample Input 2

4 3
CABA

Sample Output 2

CAbA

Solution in Common Lisp (SBCL 2.0.3) (judge verdict: Accepted)

(let ((n (read))
      (k (read)))
  (loop :for i :from 1 :to n
        :for x := (read-char)
        :do (if (= i k)
                (format t "~A" (char-downcase x))
                (format t "~A" x))
        :finally (format t "~%")))