Problem:
Score : 300 points

Problem Statement

You are given four integers A, B, C, and D. Find the number of integers between A and B (inclusive) that can be evenly divided by neither C nor D.

Constraints

1\leq A\leq B\leq 10^{18}

1\leq C,D\leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

A B C D

Output

Print the number of integers between A and B (inclusive) that can be evenly divided by neither C nor D.

Sample Input 1

4 9 2 3

Sample Output 1

2

5 and 7 satisfy the condition.

Sample Input 2

10 40 6 8

Sample Output 2

23

Sample Input 3

314159265358979323 846264338327950288 419716939 937510582

Sample Output 3

532105071133627368

Solution in PHP (5.6.30) (judge verdict: Wrong Answer)

<?php 
fscanf(STDIN, "%d %d %d %d", $a,$b,$c,$d);
$cNum = floor($b/$c) - floor(($a-1)/$c);
$dNum = floor($b/$d) - floor(($a-1)/$d);

$arr = array($d, $c);
$flag = 0;
$i = 0;
while ($flag == 0){
  $rem = $arr[$i]%$arr[$i+1];
  if($rem == 0){
    $flag = 1;
    $n = $arr[$i+1];
  }else {
    $arr[] = $rem;
    $i++;
  }
}
$m = $c*$d/$n;
$cd = floor($b/$m) - floor(($a-1)/$m);

$add = $cNum+$dNum-$cd;

$str = sprintf("%.0f", $b-$a+1-$add);

var_dump($str);
?>