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 java.io.PrintWriter

val pw = PrintWriter(System.out)
fun main(args: Array<String>) {
    func()
    pw.flush()
}
fun println(value: Any) { pw.println(value) }

//ABC129x_x
fun func() {
    val (N, K) = listOfInt()
    var C = next().substring(0, N).toCharArray()
    C[K-1] = C[K-1].toLowerCase()
    println("${C.joinToString(separator = "")}")
}

fun next() = readLine()!!
fun listOfString() = next().split(" ")
fun listOfInt() = listOfString().map { Integer.parseInt(it) } //{ it.toInt() }