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# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using static System.Console;
using static System.Math;

class MainClass
{
    static void Main()
    {
        var abcd = ReadLine().Split().Select(long.Parse).ToArray();
        var a = abcd[0]-1;
        var b = abcd[1];
        var c = abcd[2];
        var d = abcd[3];
        var lcm = LCM(c, d);
        WriteLine(b-a -(b/c - a/c + b/d - a/d - (b/lcm-a/lcm)));
    }
    static long Gcd(long a,long b)
    {
        return b == 0 ? a : Gcd(b, a % b);
    }
    static long LCM(long a, long b)
        => a / Gcd(a, b) * b;
}