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;

class Program
{
    static void Main(string[] args)
    {
        var ABCD = ReadLine().Split(' ').Select(s => long.Parse(s)).ToArray();
        var (A, B, C, D) = (ABCD[0], ABCD[1], ABCD[2], ABCD[3]);

        static long Gcd(long a, long b) => (b != 0) ? Gcd(b, a % b) : a;
        static long Lcm(long a, long b) => a / Gcd(a, b) * b;
        static long GetCDX(long x, long c, long d) => x - (x / c) - (x / d) + (x / Lcm(c, d));

        var ans = GetCDX(B, C, D) - GetCDX(A - 1, C, D);

        WriteLine(ans);
    }
}