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.Collections.Generic;
using System.Linq;

namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            var ss = Console.ReadLine().Split();
            var N = int.Parse(ss[0]);
            var K = int.Parse(ss[1]);

            var S = Console.ReadLine();

            var diff = 'A' - 'a';
            for (int i = 0; i < N; i++)
            {
                if (i == K - 1)
                {
                    Console.Write(Char.ToLower(S[i]));
                }
                else
                {
                    Console.Write(S[i]);
                }
            }

            Console.WriteLine();
        }
    }
}