/**
*k1大矩形的宽
*c1大矩形的长
*k2小矩形的宽
*c2小矩形的长
*/
function countRectangles($k1, $c1, $k2, $c2) {
        $dp = array();
        for ($i = 0; $i <= $c1; $i++) {
            $dp[$i] = array_fill(0, $k1+1, 0);
        }

        for ($i = 1; $i <= $c1; $i++) {
            for ($j = 1; $j <= $k1; $j++) {
                $max_num = 0;
                for ($k = 1; $k <= $i; $k++) {
                    for ($l = 1; $l <= $j; $l++) {
                        $num_k = floor(($i - $k + 1) / $c2);
                        $num_l = floor(($j - $l + 1) / $k2);
                        $max_num = max($max_num, $dp[$k-1][$l-1] + $num_k * $num_l);
                    }
                }
                $dp[$i][$j] = $max_num;
            }
        }

        return $dp[$c1][$k1];
    }