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: Accepted)

A, B, C, D = gets.split.map(&:to_i)

num = B - A + 1

a1 = B / C
a2 = (A - 1) / C
a3 = a1 - a2

b1 = B / D
b2 = (A - 1) / D
b3 = b1 - b2

lcm = C.lcm(D)

c1 = B / lcm
c2 = (A - 1) / lcm
c3 = c1 - c2

puts num - (a3 + b3 - c3)