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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.*;

public class Main{
    public static long gcd(long n, long m){
        if(m < n){
            return gcd(m,n);
        }
        if(n==0){
            return m;
        }
        return gcd(n, m%n);
    }
    public static void main(String args[]){
        Scanner scanner = new Scanner(System.in);
        long A = scanner.nextLong();
        long B = scanner.nextLong();
        long C = scanner.nextLong();
        long D = scanner.nextLong();

        long lcmCD = C * D / gcd(C,D);

        long divC = Math.floorDiv(B, C) - Math.floorDiv(A-1, C);
        long divD = Math.floorDiv(B, D) - Math.floorDiv(A-1, D);
        long divCD = Math.floorDiv(B, D*C) - Math.floorDiv(A-1, D*C);
        long undiv = B - A + 1 - divC - divD + divCD;

        System.out.println(undiv);
    }
}