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;

@s = split(/ /, <>);

$lcm = Math::BigInt::blcm($s[2], $s[3]);

$ok = (int($s[1] / $s[2]) - int(($s[0] - 1) / $s[2])) + (int($s[1] / $s[3]) - int(($s[0] - 1) / $s[3])) - (int($s[1] / $lcm) - int(($s[0] - 1) / $lcm));

$ans = $s[1] - ($s[0] - 1) - $ok;

print "$ans\n";