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)

require 'rational'
# a,b,c = 3.times.map(gets.to_i)
a,b,c,d=gets.strip.split.map(&:to_i)

#.inject(:+)

#cnt=0
#while as.all?(|x|x.even?) do
  # cnt=cnt.succ
# end

# ans = (1..n)
#   .map{|i|[i,j]}
#   .select{|d|a <= d[1] && d[1]<= b}
#   .inject(0){|sum,d|sum+

def baisu(min,max,e)
  return (max/e)-(min/e)
end



puts b-a-(baisu(a,b,c)+baisu(a,b,d)-baisu(a,b,c.lcm(d)))