Panda was infuriated when he found that the first submission to the problem in the IceAge Contest was not his.
So he challenged the first submitter for a challenge. There are plates boards marked with numbers from L to R.
Both the contestants will be given a number each, let say X and Y. The task is simple, they have to shoot the boards which contain a multiple of a number which has been given to them. However, one board can be shot only once in total (including shooting by both the contestants).
Your task is to calculate the number of bullets required for the contest.

Constraints :
1 <= L <= R <= 10 ^ 18
1 <= X, Y <= 10 ^ 6

Input:
First-line contains four integers: L R X Y

Output:
Print single integer (the count of bullets)

Sample Test Case 1

Input:
1 10 2 3

Output:
7

Explanation:
One bullet will be required for boards: 2 3 4 6 8 9 10