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.*;
import java.io.*;

class Main {

	void solve () {

		int n = in.nextInt(), k = in.nextInt();
		char[] s = in.next().toCharArray();
		s[k-1] = Character.toLowerCase(s[k-1]);
		out.println(String.valueOf(s));
		
	}
	
	public static Scanner in = new Scanner(System.in);
	public static PrintWriter out = new PrintWriter(System.out);
	public static void main(String[] args) {
		new Main().solve();
		out.flush();
	}

}