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: Runtime Error)

using System;
using System.Text;


namespace ABC126
{
    class Program
    {
        static int Main(string[] args)
        {
            ProblemB();
            return 0;
        }

        static void ProblemB()
        {
            int input = int.Parse(System.Console.ReadLine());
            string answer;

            int ba, dc;
            ba = input % 100;
            dc = (input - ba)/100;

            //YYMM
            if(ba <= 12 && ba >= 1)
            {
                if(dc <= 12 && ba >= 1)
                {
                    answer = "AMBIGUOUS";
                }
                else
                {
                    answer = "YYMM";
                }

            }
            //notYYMM
            else
            {
                if(dc <=12 && dc >= 1)
                {
                    answer = "MMYY";
                }
                else
                {
                    answer = "NA";
                }
            }

            Console.WriteLine(answer);
        }

        static int ProblemA()
        {
            string[] K = System.Console.ReadLine().Split(' ');
            string S = System.Console.ReadLine();
            string L = S.ToLower();
            char[] Answer = new char[S.Length];

            for(int i = 0; i < S.Length; i++)
            {
                if(i == int.Parse(K[1])-1)
                {
                    Answer[i] = L[i];
                }
                else
                {
                    Answer[i] = S[i];
                }
            }

            Console.WriteLine(Answer);

            return 0;
        }
    }


}