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;
class Program
    {
        static void Main(string[] args)
        {
            //とりあえず数値を読み込む
            string[] input = Console.ReadLine().Split(' ');
            int n = int.Parse(input[0]);
            int k = int.Parse(input[1]);


            //得点に対して確率を出す
            double sum = 0;

            for (int i = 1; i <= n; i++)
            {
                double purpose = k / i;
                int j = 0;
                //出さないとならない表の数を求める
                while (purpose >= Math.Pow(2, j))
                {
                    j++;
                }
                //確率を出す
                double temp = Math.Pow(1 / 2, j);
                //確率を足す
                sum += temp;

            }

            //結果を示す
            Console.WriteLine(sum);
        }
    }