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 Program{
    public static void Main(){
        string[] line = Console.ReadLine().Trim().Split();
        var n = int.Parse(line[0]);
        var k = int.Parse(line[1]);
        string s = Console.ReadLine();
        char[] c = s.ToCharArray();
        c[k - 1] = Char.ToLower(c[k - 1]);
        s = new string(c);
        
        Console.WriteLine("{0}", s);
    }
}