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)

start_num,end_num, div1, div2 =  gets.split(' ').map{|x| x.to_i }
#puts (start_num..end_num).to_a.count{|x| x % div1 != 0 && x % div2 != 0}
div1_wari = end_num / div1 - (start_num - 1) / div1
div2_wari = end_num / div2 - (start_num - 1) / div2
lcm = div1.lcm(div2)
lcm_wari = end_num / lcm - (start_num - 1) / lcm
puts (end_num - start_num + 1) - (div1_wari + div2_wari - lcm_wari)