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 CSharp
{
    public static void Main()
    {
        Kyopuro chokudai = new Kyopuro();
        chokudai.AtCoder();
    }
}

public class Kyopuro
{
    public void AtCoder()
    {
        string[] input;
        input = Console.ReadLine().Split(' ');

        int n, k;
        n = int.Parse(input[0]);
        k = int.Parse(input[1]) - 1;

        string s = Console.ReadLine();

        string x = "";
        for(int i=0; i<n; i++)
        {
            if(i == k)
            {
                if (s[i] == 'A') x = "a";
                if (s[i] == 'B') x = "b";
                if (s[i] == 'C') x = "c";
                Console.Write(x);
            }
            else Console.Write(s[i]);
        }

        Console.WriteLine();
    }
    public static void DebugWL(object x) { System.Diagnostics.Debug.WriteLine(x); }
}