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: Runtime Error)

from fraction import gcd
A, B, C, D = map(int, input().split())
BdivC, BdivD = B // C, B // D
AdivC, AdivD = A // C, A // D
GCD = gcd(C, D)
BdivCD, AdivCD = B // ((C * D) // GCD), A // ((C * D) // GCD)
N1 = BdivC + BdivD - BdivCD
N2 = AdivC + AdivD - AdivCD
ans = (B - A) - (N1 - N2)
if(A % C != 0): ans += 1
print(ans)