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;

class abc126_A
{
    static void Main(string[] args)
    {
        var line = readLongs();
        var QN = line[0];
        var QK = line[1];
        var QS = Console.ReadLine();

        var a = QS.ToCharArray();
        a[QK-1] = Char.ToLower(a[QK-1]);
        var str = String.Join("", a);
        Console.WriteLine(str);
    }

    
    static long[][] readLongsN(int N) { return Enumerable.Range(0, N).Select(x => readLongs()).ToArray(); }

    static long readLong() { return long.Parse(Console.ReadLine()); }

    static long[] readLongs() { return Console.ReadLine().Split(' ').Select(s => long.Parse(s)).ToArray(); }

}