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 Ruby (2.3.3) (judge verdict: Wrong Answer)

a,b,c,d=gets.split.map(&:to_i)
a_c = a/c
a_d = a/d
a_cd = a/(c.lcm(d))
b_c = b/c
b_d = b/d
b_cd = b/(c.lcm(d))

sum = (b_c + b_d - b_cd) - (a_c + a_d - a_cd)
sum += 1 if a % c == 0
sum += 1 if a % d == 0
sums = b-a+1
puts sums-sum