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;

class plogram
{
    static void Main()
    {

        string str = Console.ReadLine();
        string[] array = str.Split(' ');

        int N = int.Parse(array[0]);
        int K = int.Parse(array[1]);

        string S = Console.ReadLine();

        string i = S.Substring(0, K - 1);
        string j = S.Substring(K-1, 1);
        if (j == "A")
        {
            j = "a";
        }
        else if (j == "B")
        {
            j = "b";
        }
        else
        {
            j = "c";
        }
        string k = S.Substring(K, S.Length-K);

        Console.WriteLine(i + j + k);
    }
}