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)
l=C.lcm(D)
cz = (B.to_f/C).floor - (A.to_f/C).ceil + 1
if A>B
  p 0
elsif C==D
  p B-A+1-cz
else
  dz = (B.to_f/D).floor - (A.to_f/D).ceil + 1
  lz = (B.to_f/l).floor - (A.to_f/l).ceil + 1
  p B-A+1 - (cz+dz-lz)
end