using System;

public class Program

{

    public static void Main(string[] args)

    {

        int x=0;

        int y=0;

        char[,] coordinates = new char[20,20];

        while (true)

        {

            //user must enter 2 3 for example.

            string[] response = Console.ReadLine().Split(new[]{" "}, StringSplitOptions.RemoveEmptyEntries);

            if (response[0].ToLower() == "stop")

                break;

​

            x = int.Parse(response[0]);

            y = int.Parse(response[1]);

            coordinates[x,y] = '*';

        }

        //Print the output

        for(var i = 0; i < 20; i++)

        {

            for( var j = 0; j < 20; j++)

                if (coordinates[i,j] == (char)0)

                    Console.Write('#');

                else 

                    Console.Write(coordinates[i,j]);

            Console.WriteLine();

        }

    }

}