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 Scala (2.11.7) (judge verdict: Accepted)

object Main extends App {
  val in = scala.io.Source.stdin.getLines.toSeq
  val ls = in(0).split(' ').map(_.toInt)
  val K = ls(1) - 1
  val S = in(1).toArray
  val diff = ('A'.toInt - 'a'.toInt)
  if('A' <= S(K) && S(K) <= 'C' )
  S(K) = (S(K).toInt - diff).toChar
  else
  S(K) = (S(K).toInt + diff).toChar
  S.map(print)
  println("")
}