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)

from fractions import gcd

def debug(*args):
    import sys
    #print(*args, file=sys.stderr)

def solve(A, B, C, D):
    L = C * D // gcd(C, D)
    A-=1
    debug("A=%d, B=%d, C=%d, D=%d" %(A,B,C,D))
    debug((B//C, A//C), (B//D, A//D) , (B//L , A//L))
    debug((B//C - A//C), (B//D - A//D) , (B//L - A//L))
    return B-A- ((B//C - A//C) + (B//D - A//D) - (B//L - A//L))

def main():
    A, B, C, D = [int(x) for x in input().split()]
    print(solve(A, B, C, D))
    pass

main()