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;
using System.Numerics;
using System.Linq;
using System.Collections.Generic;
using System.Text;

namespace debug
{
    class ProgramA
    {
        static void Main(string[] args)
        {

            //入力
            string[] n = Console.ReadLine().Split(' ');
            string s  = Console.ReadLine();

            //
            int num = int.Parse(n[1]) - 1;
            for(int i = 0;i < int.Parse(n[0]);i++)
            {
                int temp = s[i];
                if(i == num)
                {
                    temp += 32;
                    Console.Write((char)temp);
                }
                else
                {
                    Console.Write((char)temp);
                }
            }

        }
    }
}