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: Wrong Answer)

<?php
    fscanf(STDIN, "%d %d", $n, $k);
    $s = fgets(STDIN);
    $array = explode(' ', $s);
    $repNum = $k - 1;
    if($array[$repNum] === 'A'){
        $array[$repNum] = 'a';
    }elseif($array[$repNum] === 'B'){
        $array[$repNum] = 'b';
    }elseif($array[$repNum] === 'C'){
        $array[$repNum] = 'c';
    }
    echo implode($array);
?>