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)

#C
import math
a, b, c, d = map(int, input().split())

def gcd(x, y):
    if x < y:
        x, y = y, x
    while a % b != 0:
        a, b = b, a % b

a-=1
cd=c*d//math.gcd(c,d)
ans = b - (b // c) - (b // d) + (b // cd)
ans -= a - (a // c) - (a // d) + (a // cd)

print(ans)