I'd make an array:
$groups = array();
$groups['groupA'] = array('min'=>1,'max'=>100);
$groups['groupB'] = array('min'=>1,'max'=>100);
And then
foreach($groups as $label => $group)
{
if($input >= $group['min'] && $input <= $group['max'])
{
echo "You are in group $label";
break;
}
}
or you can put them in a database