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: Wrong Answer)

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;

namespace atcoder
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] input = Console.ReadLine().Split(' ');
            
            int N = int.Parse(input[1]);
            int K = int.Parse(input[0]);
            int res = 0;
            string X = N.ToString();
            string Y = K.ToString();
            
            for(int i = K; i <= N; i++)
            {
                res++;
            }
            string S = "ABC";
            if (S == X)
            {
                Console.Write(X, Y);
                Console.Write(S.ToLower());
            }
        }
    }
}