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 c
{
    static void Main()
    {
        var ab = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
        var s = Console.ReadLine();
        Console.WriteLine(s.Substring(0, ab[1] - 1) + s.Substring(ab[1] - 1, 1).ToLower() + s.Substring(ab[1]));
    }
}