Empty console window?

[Am0n]

Hello everybody
I am reading a book by Rob miles.
I'm new to programming, entered this code

using System;
class GlazerCalc
{
static void Main()
{
double width, height, woodLength, glassArea;
string widthString, heightString;
widthString = Console.ReadLine();
width = double.Parse(widthString);
heightString = Console.ReadLine();
height = double.Parse(heightString);
woodLength = 2 * ( width + height ) * 3.25 ;
glassArea = 2 * ( width * height ) ;
Console.WriteLine ( "The length of the wood is " +
woodLength + " feet" ) ;
Console.WriteLine( "The area of the glass is " +
glassArea + " square metres" ) ;
}
}

And when I pressed F5, an empty console window popped up..
What seems to be the problem? Thank you.