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;
namespace 令和{
    class ABC{
        static void Main(){
            string[] n_k = Console.ReadLine().Split();
            int n = int.Parse(n_k[0]);
            int k = int.Parse(n_k[1]);
            char[] s = Console.ReadLine().ToCharArray();
            if(s[k-1]=='A'){s[k-1] = 'a';
            }else if(s[k-1]=='B'){
s[k-1] = 'b';
            }else{
s[k-1] = 'c';
            }
            Console.WriteLine(new String(s));
            
        }
    }
}