Limit The File Size That Can Be Uploaded Using FileUploda Control?

I want to limit the file size that can be uploaded using FileUploda Control,How to do dat?

Code:

protected void UploadBtn_Click(object sender, EventArgs e)
{
if (FileUpLoad1.HasFile)
{

FileUpLoad1.SaveAs(@"C: emp" + FileUpLoad1.FileName);
Label1.Text = "File Uploaded: " + FileUpLoad1.FileName ;
}
else
{
Label1.Text = "No File Uploaded.";
}
}