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;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp5
{

    class Program
    {
        static void Main(string[] args)
        {
            string S = Console.ReadLine();
            string[] line = S.Split(' ');
            int N = int.Parse(line[0]);
            int K = int.Parse(line[1]);
            S = Console.ReadLine();
            char[] C = new char[N];

            for(int i=0; i<N; i++)
            {
                C[i] = S[i];
                if (i != K - 1)
                {
                    Console.Write(C[i]);
                }
                else
                {
                    C[i] = Char.ToLower(C[i]);
                    Console.Write(C[i]);
                }

            }

            Console.WriteLine();


        }
    }
}