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.*;

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();
        char s = S.charAt(K-1);
        String sn = String.valueOf(s);
        if(sn.equals("A")){
            sn = "a";
        }
        else if(sn.equals("B")){
            sn = "b";
        }
        else if(sn.equals("C")){
            sn = "c";
        }

        if(K==1){
            System.out.println(sn + S.substring(1));
        }
        else if(K==2){
            System.out.println(S.charAt(0) + sn + S.substring(2));
        }
        else if(K>=3){
            System.out.println(S.substring(0, K-1) + sn + S.substring(K));
        }
    }
}