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 ABC126_A
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] info = Console.ReadLine().Split(' ').Select(str => int.Parse(str)).ToArray();
            int n = info[0];
            int k = info[1] - 1;

            char[] s = Console.ReadLine().ToCharArray();

            s[k] = Char.ToLower(s[k]);

            string result = string.Join("", s);
            Console.WriteLine(result);
            Console.ReadLine();

        }
    }
}