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)

def gcd(a, b):
        while b:
                a, b = b, a % b
        return a

def lcm(a, b):
#    return a * b // math.gcd (a, b)
    return a * b // gcd (a, b)

a, b, c, d = map(int, input().split())
count = 0
common = 0
dif = b - a
divC = dif // c
divD = dif // d
kobai = lcm(c, d)
divKobai = dif // kobai

#for i in range(a, b, c):
# for i in range(a, b + 1):
#     if i % c == 0 and i % d == 0:
#         common += 1

#print(dif - (divC + divD - common))
print(dif - (divC + divD - divKobai))