Making a button appear when a number is entered into the form

[N.style]

From this topic: how do i make an invisible text input box visible on hover?I read this problem and it helps me a lot and I came with this code:HTML:\[code\]<div id="box1"> <form action=""> <input type="string" name="amount" /> </form></div> \[/code\]CSS:\[code\]#box1 { width:100px; height:30px;}#box1:hover input { display:block; padding:3px;}#input { display:none;}\[/code\]My problem is that once I input the amount, I want the confirm button to show up. Is this possible?Thanks in advance.