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.*;
class Main{
	public static void main(String[] args){
    	Scanner scan = new Scanner(System.in);
      	int n = scan.nextInt();
      	int k = scan.nextInt();
      	String word = scan.next();
            
      	String ans = word.substring(0,k-1) + word.substring(k-1,k).toLowerCase() + word.substring(k,n);
       System.out.println(ans);
    }
}