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 stdIn = new Scanner(System.in);
		int N = stdIn.nextInt();
		int K = stdIn.nextInt();
		String S = stdIn.next();
		String[] words = S.split("", 0);
		if(words[K-1].equals("A")) {
			words[K-1] = "a";
		}
		else if(words[K-1].equals("B")) {
			words[K-1] = "b";
		}
		else if(words[K-1].equals("C")) {
			words[K-1] = "c";
		}
		for(int i = 0; i < N; i++) {
			System.out.print(words[i]);
		}

	}

}