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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Linq;
using System.Collections.Generic;

public class Hello{
    public static void Main(){
        string[]array=Console.ReadLine().Split(' ');
        var A=long.Parse(array[0]);
        var B=long.Parse(array[1]);
        var C=long.Parse(array[2]);
        var D=long.Parse(array[3]);
        
        long temp=0;
        long a=C;
        long b=D;
        if(a<b){
            temp=a;
            a=b;
            b=temp;
        }
        
        long r=a%b;
        
        while(r!=0){
            a=b;
            b=r;
            r=a%b;
        }
        
        long E=(C*D)/b;
        
        long num1=B/C-(A-1)/C;
        long num2=B/D-(A-1)/D;
        long num3=B/E-(A-1)/E;
        
        long sum=(B-A+1)-(num1+num2-num3);
        
        Console.WriteLine(sum);
    }
}