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# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Linq;
using System.Collections.Generic;

namespace ABC
{
    class ProgramA
    {
        static void Main(string[] args)
        {
            var inputs = Console.ReadLine().Split(" ");
            var n = long.Parse(inputs[0]);
            var k = long.Parse(inputs[1]);

            var s = Console.ReadLine();

            var result = "";

            for (var i = 0; i < n; i++)
            {
                result += i == k - 1 ? s[i].ToString().ToLower() : s[i].ToString();
            }

            Console.WriteLine(result);
        }
    }
}