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.split.map(&:to_i)

divc = (b - a + 1) / c
if a <= (divc + 1) * d && (divc + 1) * c <= b
  divc += 1
end

divd = (b - a + 1) / d
if a <= (divd + 1) * d && (divd + 1) * d <= b
  divd += 1
end

divcd = (b - a + 1) / (c * d)
if a <= (divcd + 1) * (c * d) && (divcd + 1) * (c * d) <= b
  divcd += 1
end

puts (b - a + 1) - divc - divd + divcd