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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
public class ABC126A {
    public static void Main() {
        int N, K;
        string[] str = System.Console.ReadLine().Split(' ');
        N = int.Parse(str[0]);
        K = int.Parse(str[1]);
        string S = System.Console.ReadLine();
        string ans = "";
        for(int i = 0; i< S.Length; i++) {
            if (i == K - 1) {
               ans += char.ToLower(S[K - 1]);
            } else {
               ans += S[i];
            }
        }
        System.Console.WriteLine(ans);
    }
}