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;
using System.Linq;

public class Prog
{
    public static void Main()
    {
        //var input = Console.ReadLine().Split();
        //int[] X = Array.ConvertAll(input, int.Parse);
        var input = Console.ReadLine().Split();
        int N = int.Parse(input[0]);
        int K = int.Parse(input[1]);
        string S = Console.ReadLine();
        String ans = "";
        for(int i = 0; i < N; i++)
        {
            if(K == i + 1)
            {
                if(S[i] == 'A')
                {
                    ans += 'a';
                }else if(S[i] == 'B')
                {
                    ans += 'b';
                }
                else
                {
                    ans += 'c';
                }
            }
            else
            {
                ans += S[i];
            }
        }
        Console.WriteLine(ans);
    }
}

//Array.ConvertAll(int.Parse)