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
//最大公約数
function gcd($m, $n){
    if($n > $m) list($m, $n) = array($n, $m);
     
    while($n !== 0){
        $tmp_n = $n;
        $n = $m % $n;
        $m = $tmp_n;
    }
    return $m;
}
 
//最小公倍数
function lcm($m, $n){
    return $m * $n / gcd($m, $n);
}

	fscanf(STDIN, '%d %d %d %d', $A, $B, $C, $D);

	$lcm = lcm($C, $D);
    
    $temp1 = floor($A / $lcm);
    $temp2 = floor($B / $lcm);
    
    $temp3 = floor($A / $C);
    $temp4 = floor($B / $C);
    
    $temp5 = floor($A / $D);
    $temp6 = floor($B / $D);
    
    $step1 = ($temp4 + $temp6) - $temp2;
    $step2 = ($temp3 + $temp5) - $temp1;
    
    $special = 0;
    
    if($A % $C == 0 && $A % $D == 0) {
        $special = 3;
    } else if($A % $C == 0) {
        $special++;
    } else if($A % $D == 0) {
        $special++;
    }
 
echo ((($B - $A) + 1) - ($step1 - ($step2 - $special)));