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 = [int(_) for _ in input().split()]

import math
def gcd(a,b):
    while b!=0:
        a,b=b,a%b
    return a
def lcm(a, b):
    return a * b / gcd(a, b)

def dvi_num(b, c):
    return math.floor(b / c)


def dvi_num2(b, c, d):
    return b - dvi_num(b,c) - dvi_num(b,d) + dvi_num(b, lcm(c, d))

ans = 0
if (A != B):
    ans = dvi_num2(B, C, D) - dvi_num2(A - 1, C, D)

print(ans)