<?php
if(!isset($_POST['firstname'])){
	include 'form.html.php';
}
else{
	$firstname=$_POST['firstname'];
	$lastname=$_POST['lastname'];
	$output="welcome to our site ".
	htmlspecialchars($firstname,ENT_QUOTES,"UTF-8").
	" ".
	htmlspecialchars($lastname,ENT_QUOTES,"UTF-8")."!";
	include 'welcome.html.php';
}