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 Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong() - 1;
        long b = sc.nextLong();
        long c = sc.nextLong();
        long d = sc.nextLong();
        long lcm = lcm(c, d);
        long e = b - a;
        long f = a / c;
        long g = a / d;
        long h = a / lcm;
        long ans1 = a - f - g + h;
        long i = b / c;
        long j = b / d;
        long k = b / lcm;
        long ans2 = b - i - j + k;
        long ans = ans2 - ans1;
        System.out.println(ans);
    }

    public static final long lcm(final long a, final long b) {
        return a * b / gcd(a, b);
    }

    public static final long gcd(long a, long b) {
        if (a < b) {
            long tmp = a;
            a = b;
            b = tmp;
        }
        long r = -1;
        while (r != 0) {
            r = a % b;
            a = b;
            b = r;
        }
        return a;
    }
}