<!DOCTYPE html>
<html>
<body>
<html>
<body>
<form action =” ” method=”post”>
<!– put–>
<div>
<label for =”input”> put </label>
<input type = “text “name = “ref_ID”>
</div>
<br/>
<!– submit–>
<div>
<label for =”submit”>submit </label>
<button type=”submit”>submit</button>
</div>
<!– result –>
<div>
<label for =”result”>result </label>
<input type = “number” name = “result” value=”<?php echo isset($result) ? $result : ”?>”>
</div>
</form>
</body>
</html>