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 PHP (7.4.4) (judge verdict: Runtime Error)

<?php
fscanf(STDIN, "%d %d", $N, $K);
fscanf(STDIN, "%s", $S);

$change_place = substr($S, $K - 1, 1);
$little_str = mb_strtolower($change_place);

echo substr_replace($S, $little_str, $K - 1, 1);
return;