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: Time Limit Exceeded)

import math
A, B, C, D = map(int, input().split())

# CでもDでも割り切れない = 全体(a) - Cで割り切れる(b) + Dで割り切れる(c) + CでもDでも割り切れる(d)
lcm = C*D // math.gcd(C, D)

a, b, c, d = B-A+1, 0, 0, 0
for i in range(A, B+1):
  if i % C == 0: b += 1
  if i % D == 0: c += 1
  if i % lcm == 0: d += 1

print(a-b-c+d)