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.Scanner;

class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    long a = Long.parseLong(sc.next());
    long b = Long.parseLong(sc.next());
    long c = Long.parseLong(sc.next());
    long d = Long.parseLong(sc.next());
    long g;
    if(c>=d){
      g = gcd(c,d);
    }else{
      g = gcd(d,c);
    }
    long l = (c/g)*(d/g)*g;
    long cnt1 = b/c-(a+c-1)/c;
    long cnt2 = b/d-(a+d-1)/d;
    long cnt3 = b/l-(a+l-1)/l;
    if(cnt1<0){
      cnt1 = 0;
    }else{
      cnt1++;
    }
    if(cnt2<0){
      cnt2 = 0;
    }else{
      cnt2++;
    }
    if(cnt3<0){
      cnt3 = 0;
    }else{
      cnt3++;
    }
    
    System.out.println(b-a+1-(cnt1+cnt2-cnt3));
    System.out.flush();
  }
  
  public static long gcd(long a,long b){
    if(b==0){
      return a;
    }else{
      return gcd(b,a%b);
    }
  }
}