Problem:
Score : 200 points

Problem Statement

You are given a string S of length N consisting of lowercase English letters, and an integer K.
Print the string obtained by replacing every character in S that differs from the K-th character of S, with *.

Constraints

1 \leq K \leq N\leq 10

S is a string of length N consisting of lowercase English letters.

N and K are integers.

Input

Input is given from Standard Input in the following format:

N
S
K

Output

Print the string obtained by replacing every character in S that differs from the K-th character of S, with *.

Sample Input 1

5
error
2

Sample Output 1

*rr*r

The second character of S is r. When we replace every character in error that differs from r with *, we get the string *rr*r.

Sample Input 2

6
eleven
5

Sample Output 2

e*e*e*

Sample Input 3

9
education
7

Sample Output 3

******i**

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

// Undone
using System;
using System.Linq;
using System.Collections.Generic;
using System.Collections;
public class Program {
  public static void Main() {
    int N = cin(); string S = ReadStr(); int K = cin();
    char keep = S[K-1];
    string ans = "";
    for (int i = 0; i < N; i++) {
      if (S[i] == keep) {
        ans += keep.ToString();
      } else {
        ans += "*";
      }
    }
    Console.WriteLine(ans);
  }

  private static List<int> _var;
  public static int cin() { if (_var == null || _var.Count() == 0) { _var = Console.ReadLine().Split(' ').Select(int.Parse).ToList<int>(); } int ans = _var[0]; _var.RemoveAt(0); return ans; }
  public static void Swap<T>(ref T a, ref T b) {T temp = a;a = b;b = temp;}
  public static string ReadStr() { return Console.ReadLine(); }
  public static int ReadInt() { return int.Parse(Console.ReadLine()); }
  public static double ReadDouble() { return double.Parse(Console.ReadLine()); }
  public static long ReadLong() { return long.Parse(Console.ReadLine()); }
  public static char ReadChar() { return Console.ReadLine()[0]; }
  public static string[] ReadStringArray() { return Console.ReadLine().Split(' '); }
  public static int[] ReadIntArray() { return Console.ReadLine().Split(' ').Select(int.Parse).ToArray(); }
  public static double[] ReadDoubleArray() { return Console.ReadLine().Split(' ').Select(double.Parse).ToArray(); }
  public static long[] ReadLongArray() { return Console.ReadLine().Split(' ').Select(long.Parse).ToArray(); }
  public static char[] ReadCharArray() { return Console.ReadLine().ToArray(); }
  public static string[] ReadCharStringArray() { return Console.ReadLine().ToCharArray().Select(c => c.ToString()).ToArray(); }
}