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 (5.6.30) (judge verdict: Accepted)

<?php
fscanf(STDIN,"%d %d",$n,$k);
fscanf(STDIN,"%s",$str);

for($i=0;$i<$n;$i++){
	$moji=substr($str,$i,1);
	if($i==$k-1){
		$out.=strtolower($moji);
	}else{
		$out.=$moji;
	}
}

echo $out;
?>