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: Wrong Answer)


def gcd(x, y):
    if y == 0:
        return x
    else:
        return gcd(y, x % y) #再帰定義

def lcm(x, y):
    return (x * y) // gcd(x, y)


A,B,C,D = map(int,input().split())

diffs = B - A

if diffs < min(C,D):
    print(diffs + 1)
    exit()

C_num = diffs // C
D_num = diffs // D

sc = lcm(C,D)


sc_num = diffs // sc


print(diffs - (C_num + D_num - sc_num))