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: Accepted)

# 最大公約数
def gcd(a, b):
    while b != 0:
        a, b = b, a % b
    return a


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

a,b,c,d = input().split(' ')

a = int(a)
b = int(b)
c = int(c)
d = int(d)

hoge = lcm(c,d)

counter = 0

counter = counter + ((b // c) + (b // d) - (b // hoge))
counter = counter - (((a - 1) // c) + ((a - 1) // d) - ((a - 1) // hoge))

print(b - a + 1 - counter)