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# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
 
class Program{
  static void Main(){
    
    string[] nk = Console.ReadLine().Split(' ');
    string str = Console.ReadLine();
    char[] cs = str.ToCharArray();
    
    int n=int.Parse(nk[0]);
    int k=int.Parse(nk[1]);
    
    cs[k-1]=Char.ToLower(cs[k-1]);
    
    for(int i=0;i<n;i++){
    Console.Write(cs[i]);
    }
  }
}