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)

a, b, c, d = map(int, input().split())

#a,bの最大公約数
def gcd(a, b):
    while b:
        a, b = b, a % b
    return a

#a,bの最小公倍数
def lcm(a, b):
    return a * b // gcd (a, b)

def main():
    left = (b -int(b/c) -int(b/d) +int(b/lcm(c,d)))
    right = ((a-1) -int((a-1)/c) -int((a-1)/d) +int((a-1)/lcm(c,d)))
    print(left - right)
main()