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 (2.7.1) (judge verdict: Accepted)

a,b,c,d = gets.chomp.split(' ').map(&:to_i)

n = b - a + 1
k = c.lcm(d) #最小公倍数

if(a % d == 0)
d_1 = (b/d - a/d + 1) #dで割れる個数
else
d_1 = (b/d - a/d) #dで割れる個数
end

if(a % c == 0)
c_1 = (b/c - a/c + 1) #cで割れる個数
else
c_1 = (b/c - a/c) #cで割れる個数
end

if(a % k == 0)
k_1 = (b/k - a/k + 1) #cとdで割れる個数
else
k_1 = (b/k - a/k) #cとdで割れる個数
end

m = c_1 + d_1 - k_1

puts n - m