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)

A,B,C,D = map(int,input().split())
from fractions import gcd
CD = int(C*D/gcd(C,D))

B_both = B//(CD)
B_C = B//C
B_D = B//D
first_term = B-(B_C+B_D-B_both)
A -= 1
A_both = A//(CD)
A_C = A//C
A_D = A//D
second_term = A-(A_C+A_D-A_both)

print(first_term-second_term)