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 fractions
a, b, c, d = map(int, input().split())
ans = 0

def lcm(x, y):
    return (x * y) // fractions.gcd(x, y)

cd = lcm(c, d)

# cの倍数とdの倍数の個数を数える
# cの倍数dの倍数の個数を引く
ca = ((a-1) // c)
print(ca)
cb = (b // c)
print(cb)
tmp_c = cb - ca

da = (a // d)
print(da)
db = (b // d)
print(db)
tmp_d = db - da

cda = (a // cd)
print(cda)
cdb = (b // cd)
print(cdb)
tmp_cd = cdb - cda
ans = b - a + 1 - (tmp_c + tmp_d - tmp_cd)

print(ans)