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())

x = c
y = d
while y:
    x, y = y, x % y
gcd = x
lcm = c * d // gcd

sc = (b // c - (a-1) // c)
sd = (b // d - (a-1) // d)
slcm = b // lcm - a // lcm
print(b-a+1 - sc - sd + slcm)

# 1 2 3 4 5 6 7 8 9
#   x   x   x   x
#     x     x     x