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.Text;
using System.Numerics;

namespace SolutionCS
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] inS = Console.ReadLine().Split(' ');
            int in0 = int.Parse(inS[0]);
            int in1 = int.Parse(inS[1]);

            string str = Console.ReadLine();

            for (int i = 0; i < str.Length; i++)
            {
                if ((i + 1) != in1)
                {
                    Console.Write("{0}", str[i]);
                }
                else
                {
                    Console.Write("{0}", (char)(str[i] - 'A' + 'a'));
                }
            }
        }
    }
}