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

while ($stdin = fgets(STDIN)) {
    $line[] = trim($stdin);
}
foreach ($line as $key => $value) {
    $data[] = explode(' ', $value);
}

foreach ($data as &$line) {
    $line = array_map(function($val) { return (int)$val; }, $line);
}


$A = $data[0][0];
$B = $data[0][1];
$C = $data[0][2];
$D = $data[0][3];

function f($n, $C, $D) {
    $deathByC = intdiv($n, $C);
    $deathByD = intdiv($n, $D);
    $lcm = lcm($C, $D);
    $deathByCD = intdiv($n, $lcm);
    return $n - $deathByC - $deathByD + $deathByCD;
}

//最大公約数
function gcd($a, $b) {
    if ($b === 0) {
        return $a;
    }
    return gcd($b, $a % $b);
}
 
//最小公倍数
function lcm($m, $n){
    return $m * $n / gcd($m, $n);
}

$left = f($A - 1, $C, $D);
$right = f($B, $C, $D);

var_dump($right, $left);

$ans = $right - $left;

printf('%d', $ans);