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.strip.split.map(&:to_i)

all = B - A + 1

def count(m)
    m_min = (A.to_f / m).ceil.to_i * m
    m_max = (B.to_f / m).floor.to_i * m

    return (m_max - m_min) / m + 1
end

ccnt = count(C)
dcnt = count(D)
cdcnt = count(C.lcm(D))

result = all - ccnt - dcnt + cdcnt

puts result