$optionsMonth = array('options'=>array('min_range'=>1, 'max_range'=>12));
$optionsYear = array('options'=>array('min_range'=>1900, 'max_range'=>9999));

if ((filter_input(INPUT_GET, 'month', FILTER_VALIDATE_INT, $optionsMonth))&&(filter_input(INPUT_GET, 'year', FILTER_VALIDATE_INT, $optionsYear))){
    $month = filter_input(INPUT_GET, 'month', FILTER_VALIDATE_INT, $optionsMonth );
    $year = filter_input(INPUT_GET, 'year', FILTER_VALIDATE_INT, $optionsYear);
} else {
    $datetime = new Datetime('NOW');
    $month = $datetime->format('m');
    $year = $datetime->format('Y');
}