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 PHP7 (7.0.15) (judge verdict: Accepted)

<?php
// $n = (int)trim(fgets(STDIN));

$input = explode(' ', trim(fgets(STDIN)));

$n = (int)$input[0];
$k = (int)$input[1];
$s = trim(fgets(STDIN));

$map = [
	'A' => 'a',
	'B' => 'b',
	'C' => 'c',
];
$s[$k-1] = $map[$s[$k-1]];

echo $s;