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.chomp.split.map(&:to_i)

c_cnt = b/c - (a-1)/c
d_cnt = b/d - (a-1)/d

g = c.lcm(d)
if g == c || g == d
    puts (b - a + 1) - (c_cnt + d_cnt)
    exit
end

g_cnt = b/g - (a-1)/g
puts (b - a + 1) - (c_cnt + d_cnt - g_cnt)