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.Linq;//リストの使用
using System.Collections.Generic;
using System.Text;//テキストの高速出力に必要
class Program
{
	static void Main()
	{
    string[] input = Console.ReadLine().Split(' ');//Splitで区切り文字を指定して複数個受け取る。
    int n = int.Parse(input[0]);
    int k = int.Parse(input[1]);
    string s = Console.ReadLine();
    char[] c = s.ToCharArray();
    if(c[k-1] == 'A') c[k-1] = 'a';
    if(c[k-1] == 'B') c[k-1] = 'b';
    if(c[k-1] == 'C') c[k-1] = 'c';
    Console.WriteLine(c);
	}
}