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 read = Array.ConvertAll(Console.ReadLine().Split(' '),int.Parse);
            var N = read[0];
            var K = read[1];
            string S = Console.ReadLine();
            String result = "";
            for(int i = 0 ; i < N ; i++)
            {
                if(i == K-1)
                {
                    result += S[i].ToString().ToLower();
                }else{
                    result += S[i];
                }
            }
            Console.WriteLine(result);
        }
    }
}