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;
using System.Collections.Generic;
using System.IO;
class Program
{
    public static long ReadInt()
    {
        return long.Parse(Console.ReadLine());
    }

    public static long[] ReadInts()
    {
        return Console.ReadLine().Split().Select(long.Parse).ToArray();
    }

    public static void Main()
    {
        var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
        Console.SetOut(sw);
       
     
        var input = ReadInts();
        var N = input[0];
        var K = input[1];
        var s = Console.ReadLine().ToCharArray();
        s[K - 1] = (char)(s[K - 1] - ('A' - 'a'));
        foreach (char c in s)
            Console.Write(c);
        Console.Out.Flush();
    }
}