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 Mondai
{
    static void Main()
    {
        var nk = Console.ReadLine().Split(' ').Select(x => Int32.Parse(x)).ToArray();
        var K = nk[1];
        var N = nk[0];
        var S = Console.ReadLine();
        var newStr = string.Empty;
        for (int i=0;i<N;++i)
        {
            if (i == K - 1) newStr += Char.ToLower(S[i]);
            else newStr += S[i];
        }
        Console.WriteLine(newStr);
    }
}