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 PHP7 (7.0.15) (judge verdict: Wrong Answer)

<?php
fscanf(STDIN, "%d %d %d %d", $A,$B,$C,$D);

$bmade=intval(floor($B/$C)+floor($B/$D)-intval(floor($B/(intval($C * $D) / gcd($C, $D)))));
$amade=intval(floor(($A-1)/$C)+floor(($A-1)/$D)-intval(floor(($A-1)/(intval($C * $D) / gcd($C, $D)))));
$ko = intval($B- $A+1);

printf("%d", intval(($ko-($bmade-$amade)))); 



function gcd($m, $n){
     
    while($n !== 0){
        $tmp_n = $n;
        $n = $m % $n;
        $m = $tmp_n;
    }
    return $m;
}
?>