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: Accepted)

import java.util.*;

public class Main {


    public static long lcm(long m, long n){
        return m*n/gcd(m,n);
    }

    public static long gcd(long c, long d){
        if (c<d){return gcd(d,c);}
        if(d==0){return c;}
        return gcd(d, c%d);
    }


    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        long a = sc.nextLong();
        long b = sc.nextLong();
        long c = sc.nextLong();
        long d = sc.nextLong();

//        long num[] = new long[b-a+1];
//        for (long i=0; i<b-a+1; i++){
//            num[i] = a+i;
//        }

        long count=0;

        long total = b-a+1;


        b = b-(b/c)-(b/d)+b/lcm(c,d);
        a = a-1-((a-1)/c)-((a-1)/d)+(a-1)/lcm(c,d);

        count = b-a;

//        long c_count=0;
//        long d_count=0;
//        long cd_count=0;
//
//
//        c_count = b/c - (a-1)/c;
//        d_count = b/d - (a-1)/d;
//        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//        if (((c-(a%c))+b%c)>c){
//            c_count += (b-a+1)/c-1;
//        }else{
//            c_count += (b-a+1)/c;
//        }
//
//
//        if (((d-(a%d))+b%d)>d){
//            d_count += (b-a+1)/d-1;
//        }else{
//            d_count += (b-a+1)/d;
//        }
//
//
//
//
//        if (((lcm(c,d)-(a%lcm(c,d))+b%lcm(c,d))>lcm(c,d))){
//            cd_count += (b-a+1)/lcm(c,d)-1;
//        }else{
//            cd_count += (b-a+1)/lcm(c,d);
//        }

//        count = (b-a+1)-c_count-d_count+cd_count;

        System.out.println(count);

    }
}