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: Wrong Answer)

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

#A-1以下のC,Dの倍数の個数
under_ac = int((A-1)/C)
under_ad = int((A-1)/D)

#B以下のC,Dの倍数の個数
under_bc = int(B/C)
under_bd = int(B/D)

#重複部分
CD = C*D

#CとDの最大公約数を求める
def gcd(a,b):
    if a<b:
        a,b = b,a
    while True:
        r = a%b
        if r ==0:
            return b
        else:
            a = b
            b = r

g = gcd(C, D)
l = int(CD/g) #C,Dの最小公倍数

#重複して引いた数
al = int((A-1)/l)
bl = int(B/l)

under_a = (A-1) - (under_ac+under_ad) + al
under_b = B - (under_bc+under_bd) + bl

print(under_b - under_a)