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 (3.4.3) (judge verdict: Runtime Error)

import math
a,b,c,d = map(int,input().split())
n = (a-1)//c #1~a-1までのcで割り切れる数
m = b//c #1~bまでのcで割り切れる数
ck = m - n #a~bまでのcで割り切れる数

o = (a-1)//d #1~a-1までのdで割り切れる数
p = b//d #1~bまでのdで割り切れる数
dk = p - o #a~bまでのdで割り切れる数

#cでもdでも割り切れる場合
e = (c * d) // math.gcd(c, d) #cとdの最小公倍数
q = (a-1)//e #1~a-1までのeで割り切れる数
r = b//e #1~bまでのeで割り切れる数
ek = r - q #a~bまでのeで割り切れる数

#cまたはdで割り切れる数
cord = ck + dk - ek

ans = b - a + 1 - cord
print(ans)