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;

namespace A
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] In = Console.ReadLine().Split(' ');
            int n = int.Parse(In[0]);
            int k = int.Parse(In[1]);
            string s = Console.ReadLine();
            string ans = "";
            for(int i=0; i < n; i++)
            {
                if (i == k - 1)
                {
                    ans += s[i].ToString().ToLower();
                }
                else
                {
                    ans += s[i];
                }
            }
            Console.WriteLine(ans);
        }
    }
}