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.util.Scanner

val sc = Scanner(System.`in`)
val n = sc.nextInt()
val k = sc.nextInt()
val s = sc.next()

fun main(args: Array<String>) {
    var rst: String = ""
    for (i in 0 until n) {
        if (k-1 == i) {
            rst += if ('A' == s[i]) {
                "a"
            } else if ('B' == s[i]) {
                "b"
            } else {
                "c"
            }
        } else {
            rst += s[i]
        }
    }
    println(rst)
}