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 Perl (v5.18.2) (judge verdict: Wrong Answer)

use Math::BigInt;
use bigint;

($a, $b, $c, $d) = split(/ /, <>);

$a--;
$lcm = Math::BigInt::blcm($c, $d);

$ok =
	  (int($b / $c) - int($a / $c))
	+ (int($b / $d) - int($a / $d))
	- (int($b / $lcm) - int($a / $lcm));

$ans = $b - $a - $ok;

print "$ans\n";