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;

namespace ABC126_A_Changing_a_Character
{
	class Program
	{
		static void Main(string[] args)
		{
			int[] input = Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray();
			int n = input[0];
			int k = input[1];
			char[] chr = Console.ReadLine().ToCharArray();

			chr[k - 1] = Char.ToLower(chr[k - 1]);
			Console.WriteLine(new string(chr));
		}
	}
}