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)

import sys
readline = sys.stdin.readline
import fractions

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

def main():
    A, B, C, D = map(int, readline().rstrip().split())
    CD = lcm_base(C, D)
    ans = B - (B//C + B//D - B//CD)
    ans -= ((A-1) - ((A-1)//C + (A-1)//D - (A-1)//CD))
    print(ans)

if __name__ == '__main__':
    main()