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 ABC126A
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] input = Console.ReadLine().Split(' ');
            int N = int.Parse(input[0]);
            int K = int.Parse(input[1]);
            string S = Console.ReadLine();

            char[] answer = new char[N];

            for (int i = 0; i < N; i++)
            {
                answer[i] = S[i];
            }

            if (answer[K-1]=='A')
            {
                answer[K-1] = 'a';
            }
            if (answer[K-1]=='B')
            {
                answer[K-1] = 'b';
            }
            if (answer[K-1]=='C')
            {
                answer[K-1] = 'c';
            }
            for (int i = 0; i < N; i++)
            {
                Console.Write(answer[i]);
            }


        }
    }
}