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)

values = gets.split(' ')
a = values[0].to_i
b = values[1].to_i
c = values[2].to_i
d = values[3].to_i

cdLcm = c.lcm(d)
cNum = (b-a)/c
dNum = (b-a)/d
lcmNum = (b-a)/cdLcm

if a%c==0
    cNum = cNum+1
end
if a%d==0
    dNum = dNum+1
end
if a%cdLcm==0
    lcmNum = lcmNum+1
end

num = b - a - cNum - dNum + lcmNum
print("#{num}\n")