Select a door:
<form action = "montyhall.php" method = "post">
<input type = "submit" name = "user_door" value = "1">
<input type = "submit" name = "user_door" value = "2">
<input type = "submit" name = "user_door" value = "3">
<input type = "hidden" name = "iteration" value = "1">
<input type = "hidden" name = "car_location" value = "2">
<input type = "hidden" name = "change_y" value = "">
<input type = "hidden" name = "change_total" value = "">

</form>