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 Program
{
	static void Main(string[] args)
	{
		// スペース区切りの整数の入力
		string[] input = Console.ReadLine().Split(' ');
		int N = int.Parse(input[0]);
		int K = int.Parse(input[1]);
		// 文字列の入力
		string S = Console.ReadLine();
		string output = S.Substring(0, K-1) + Char.ToLower(S[K-1]) + S.Substring(K);
		//出力
		Console.WriteLine(output);
	}
}