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: Wrong Answer)

import math
import fractions

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

# A以上B以下の数でXの倍数の個数
def countX(X) :
    if X > B :
        return 0
    minX = max(math.ceil(A / X),0)
    maxX = max(math.floor(B / X),0)
    return maxX - minX + 1

if C == 1 or D == 1 :
    print(0)
elif min(C,D) > B :
    print(A - B + 1)
elif max(C,D) % min(C,D) == 0 :
    Z = min(C,D)
    ans = B - A + 1 - countX(Z)
    print(ans + 1)
else :
    ans = B - A + 1

    # 最小公倍数
    Z = int(C * D / fractions.gcd(C,D))

    ans -= countX(C)
    ans -= countX(D)
    ans += countX(Z)

    print(ans)