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 Program
{
  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 result = string.Empty;
    
    for (int i = 0; i < n; i++) {
      if (i + 1 == k) {
        if (s[i] == 'A') { result += 'a'; }
        else if (s[i] == 'B') { result += 'b'; }
        else if (s[i] == 'C') { result += 'c'; }
      } else {
        result += s[i];
      }
    }
    Console.WriteLine(result);
  }
}