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.Linq;
using static System.Console;
class Program
{
    static void Main(string[] args)
    {
        int[] a = ReadLine().Split().Select(int.Parse).ToArray();
        int N = a[0];
        int K = a[1];
        string b = ReadLine();
        var c = b[K + 1];
        string s = c.ToString();
        if (s == "A")
        {
            b.Replace("a", "A");
        }else if(s == "B"){
            b.Replace("b", "B");
        }
        else
        {
            b.Replace("c", "C");
        }
        WriteLine(b);


    }
}