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)

def warizan_max(a, b)
  num = (a / b.to_f).round
  if b * num > a
    return num - 1
  else
    return num
  end
end

def warizan_min(a, b)
  num = (a / b.to_f).round
  if b * num < a
    return num + 1
  else
    return num
  end
end

a, b, c, d = gets.split.map(&:to_i)

c_wareru = warizan_max(b, c) - warizan_min(a, c) + 1
d_wareru = warizan_max(b, d) - warizan_min(a, d) + 1
lcm_wareru = warizan_max(b, c.lcm(d)) - warizan_min(a, c.lcm(d)) + 1

puts (b - a + 1) - (c_wareru + d_wareru - lcm_wareru)