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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;

public class Main {
	public static void main(String args[]) {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		try {
			String str = br.readLine();
			String s[] = str.split(" ");
			int n = Integer.parseInt(s[0]);
			int k = Integer.parseInt(s[1]);
			String ss = br.readLine();

			String s1 = ss.substring(0, k - 1);
			String s2 = ss.substring(k - 1, k);
			String s3 = ss.substring(k, ss.length());

			System.out.println(s1 + s2.toLowerCase() + s3);

			br.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}