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.Linq;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        var input = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
        var N = input[0];
        var K = input[1];
        var S = Console.ReadLine().ToCharArray();
        
        for (var i = 0; i < S.Length; i++) {
            if (i == K - 1) {
                S[i] = Char.ToLower(S[i]);
            }
            Console.Write(S[i]);
        }
    }
}