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;

class Program
{
    static void Main(string[] args)
    {
        string []input = Console.ReadLine().Split(' ');
        int N = int.Parse(input[0]);
        int K = int.Parse(input[1]);
        char[] S = Console.ReadLine().ToCharArray();
        if (S[K-1] == 'A') { S[K-1] = 'a'; }
        if (S[K-1] == 'B') { S[K-1] = 'b'; }
        if (S[K-1] == 'C') { S[K-1] = 'c'; }
        string ans = "";
        for (int i = 0; i < N; i++)
        {
            ans += S[i];
        }
        Console.WriteLine(ans);
    }
}