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;

class ABC_126_A
{
    static void Main(string[] args)
    {
        string[] input = Console.ReadLine().Split(' ');
        int N = int.Parse(input[0]);
        int K = int.Parse(input[1]);

        string s = Console.ReadLine();
        string ans = "";

        for (int i = 0; i < s.Length; i++)
        {
            if (i == K - 1)
            {
                if(s[i]=='A') ans += 'a';
                else if (s[i] == 'B') ans += 'b';
                else if (s[i] == 'C') ans += 'c';
            }
            else
            {
                ans += s[i];
            }
        }

        Console.WriteLine(ans);
    }
}