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 Python (3.8.2) (judge verdict: Accepted)

from fractions import gcd #最大公約数
A, B, C, D = map(int, input().split())
# (0~Bのうち, C,D,C*Dの倍数ではないものの数)　- (0~-Aのうち, C,D,C*Dの倍数ではないものの数)
lcm = C * D // gcd(C, D) #C,Dの最小公倍数
x = (A - 1) - (A - 1) // C - (A - 1) // D + (A - 1) // lcm
y = B - B // C - B // D + B // lcm
# (0~Bの数) - {(0~BのうちCで割り切れる数) + (0~BのうちDで割り切れる数) - (0~BのうちC,Dの最小公倍数で割り切れる数)}
print(y - x)