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)

def yaku(x, y):
    if (y == 0):
        return x
    return yaku(y ,x % y)


def calc(x, y, z):
    ny = x // y
    nz = x // z
    nyz = x // (y * z // yaku(y ,z))

    #print(ny, nz, nyz)
    #print(x - ny - nz + nyz)

    return (x - ny - nz + nyz)


a, b, c, d = list(map(int, input().split()))

rtn = calc(b,c,d) - calc(a-1,c,d)

print(int(rtn))