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;
import java.lang.String;

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();

        StringBuilder str = new StringBuilder();

        for (int i = 0; i < n; i++) {
            String si = s.substring(i,i+1);
            if(i+1 == k){
                str.append(si.toLowerCase());
            }else{
                str.append(si);
            }
        }

        System.out.println(str.toString());

        sc.close();
    }
}