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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
	  Scanner sc = new Scanner(System.in);
     int n = sc.nextInt();
     int k = sc.nextInt();
     String s = sc.next();
     sc.close();
     char ss = s.charAt(k-1);
     String sss = String.valueOf(ss);
     String lo = sss.toLowerCase();
     StringBuilder sb = new StringBuilder();
     sb.append(s);
     sb.replace(k-1, k, lo);
     String ans = sb.toString();
     System.out.println(ans);
     
	}

}