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)

# -*- coding: utf-8 -*-

import sys
import copy

sys.setrecursionlimit(1000000)


# input = sys.stdin.readline

# ~~~~~~~~~~~~~~~~~~~~~_(＾～＾ ｣ ∠)_~~~~~~~~~~~~~~~~~~~~~

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


def LCM(x, y):
    return x // GCD(x, y) * y


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

S = B - A + 1

canC = B // C - (A - 1) // C
canD = B // D - (A - 1) // D
canCD = B // LCM(C, D) - (A - 1) // LCM(C, D)

print(S - (canC + canD) + canCD)