<?php

function get_combination($number) {
    $combination = Array (
        2 => Array(2, 3, 5), 
        3 => Array(2, 3, 7), 
        4 => Array(2, 5, 7), 
        5 => Array(3, 5, 7), 
        6 => Array(2, 3, 11), 
        7 => Array(2, 5, 11),
        8 => Array(2, 7, 11), 
        9 => Array(3, 5, 11), 
        10 => Array(2, 3, 13), 
        11 => Array(2, 5, 13),
        12 => Array(2, 7, 13), 
        13 => Array(2, 3, 17), 
        14 => Array(2, 5, 17),
        15 => Array(2, 3, 19), 
        16 => Array(2, 5, 19)
    );
    return $combination[$number];
}

function task($number) {
    if ($number == 1) 
    {
        return '210 ?';
    } 
    else 
    {
        $r = get_combination($number);
        return $r[0] * $r[1] * $r[2] . ' ?';
    }
}

function solution($number) {
    if ($number == 1) 
    {
        return '2 x 3 x 5 x 7';
    } 
    else 
    {
        $r = get_combination($number);
        return $r[0] . ' x ' . $r[1] . ' x ' . $r[2] ;
    }
}

?>