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: Runtime Error)

import java.time.Instant;
import java.util.*;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

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();

		String a = S.substring(0, K-1);
		String b = S.substring(K-1, K).toLowerCase();
		String c = S.substring(K, N-1);

		String ans = S.substring(0, K-1) + S.substring(K-1, K).toLowerCase() + S.substring(K, N);
		System.out.println(ans);

	}
}