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 Perl (v5.18.2) (judge verdict: Accepted)

use strict;
use warnings;

my $n;
my $k;
($n, $k) = split /\s/, <>;
chomp(my $s = <>);

my $c = substr $s, ($k - 1) , 1;
substr($s, ($k - 1), 1) = lc $c;

print $s, "\n";