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;
using System.Text;
using System.Threading.Tasks;
public class ABC
{
    public static void Main()
    {
        int[] split = Console.ReadLine().Split().Select(int.Parse).ToArray();
        string s = Console.ReadLine();
        string output = "";
        for (int i = 0; i < s.Length; i++)
            output += (i == split[1] - 1) ? s[i].ToString().ToLower() : s[i].ToString();
        Console.WriteLine(output);
    }
}