Point does not exist in the System.Drawing namespace

I am new to C # and trying to run a sample C # program from a tutorial.

When I try to run the code below, I get the following error:

Error 1 The type or name of the namespace "Point" does not exist in the namespace "System.Drawing" (do you miss the assembly reference?) C: \ Users \ Documents \ Visual Studio 2012 \ Projects \ HelloWorld \ HelloWorld \ Class1.cs 20 28 HelloWorld

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;

namespace HelloWorld
{
    class Hello
    {
        static void Main()
        {
            Nullable<bool> b = false;
            if (b.HasValue) Console.WriteLine("b is {0}", b.Value);
            else Console.WriteLine("b is not set");

            System.Drawing.Point p = new System.Drawing.Point(20, 30);

            Console.WriteLine(b);
            Console.WriteLine("Hello World");
            Console.WriteLine("Press any key to exit");

            Console.ReadKey();
        }
    }
}