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)

($A,$B,$C,$D)=glob<>;
sub gcd{my($a,$b)=@_;$b?gcd($b,$a%$b):$a}
sub f{
	my$I=pop;
	$L=$C/gcd($C,$D)*$D;
	$I-($I/$C|0)-($I/$D|0)+($I/$L|0)
}
print f($B)- f($A-1)