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 以上 B 以下の整数のうち〜を満たすものの個数を求めよ」という問題では
(B 以下の整数のうちの〜を満たすものの個数) から
(A-1 以下の整数のうちの〜を満たすものの個数) を引く

- (全体)
+ (C の倍数の個数)
+ (D の倍数の個数)
- (C の倍数でも D の倍数でもあるものの個数)
"""

A,B,C,D = list(map(int, input().split()))

def gcd(a,b):
  if b==0:
    return a
  else:
    return gcd(b,a%b)
  
def u(n,C,D):
  return int(n - n//C - n//D + n//(C/gcd(C,D)*D))

print(u(B,C,D)-u(A-1,C,D))