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 static System.Console;
using static System.Math;
using System.Linq;

namespace Main
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] tmp = ReadLine().Split(' ').Select(int.Parse).ToArray();
            int N = tmp[0];
            int K = tmp[1];
            char[] S = ReadLine().ToCharArray();
            S[K - 1] = char.ToLower(S[K - 1]);

            WriteLine(string.Join("", S));
        }
    }
}