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;

namespace A___Changing_a_Character
{
    class Program
    {
        static void Main (string[] args)
        {
            var input = Console.ReadLine ().Split (' ');
            var n = int.Parse (input[0]);
            var k = int.Parse (input[1]);
            var s = Console.ReadLine ();
            var a = "";
            for (var i = 0; i < s.Length; i++)
            {
                if (i == k - 1)
                {
                    a += Char.ToLower (s[i]);
                }
                else
                {
                    a += s[i];
                }
            }
            Console.WriteLine (a);
        }
    }
}