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)

import scala.io.{StdIn => in}
import java.lang.{Character => char}

object Main extends App {
  val Array(n, k) = in.readLine.split(" ").map(_.toInt)
  val s = in.readLine
  val ans = s.take(k-1) + char.toLowerCase(s(k-1)) + s.drop(k)
  println(ans)
}