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 Kotlin (1.0.0) (judge verdict: Accepted)

fun main(args: Array<String>) {
  val first = readLine()!!.split(" ")
  val n = Integer.parseInt(first[0])
  val k = Integer.parseInt(first[1])
  val s = readLine()!!
  val t = s.get(k - 1)
  var after = ""
  
  when (t) {
    'A' -> {
        after = "a"
    }
    'B' -> {
        after = "b"
    }
    'C' -> {
        after = "c"
    }
  }
  
  var a1 = s.substring(0, k - 1)
  val a2 = s.substring(k)
  val result = a1 + after + a2
  println(result)
}