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)

import kotlin.comparisons.*
import java.util.*

const val MOD = 1000000007L

fun readI() = readLine()!!.toInt()
fun readL() = readLine()!!.toLong()
fun readD() = readLine()!!.toDouble()
fun readIs() = readLine()!!.split(' ').map(String::toInt)
fun readLs() = readLine()!!.split(' ').map(String::toLong)
fun readDs() = readLine()!!.split(' ').map(String::toDouble)

fun main(args: Array<String>) {
  val (n, k) = readIs()
  val s = readLine()!!.toCharArray()
  s[k - 1] = s[k - 1].toLowerCase()
  println(s.joinToString(""))
}