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.Linq;

class Class1
{
    static void Main(string[] args)
    {
        var input = Console.ReadLine().Split(' ').Select(long.Parse).ToList();
        long A = input[0];
        long B = input[1];
        long C = input[2];
        long D = input[3];

        long result = 0;

        long numb = B - (B / C + B / D) + (B / (lcm(C, D)));
        long numa = (A - 1) - ((A - 1) / C + (A - 1) / D) + ((A - 1) / lcm(C, D));

        Console.WriteLine(numb - numa);
    }

    // 最大公約数
    static long gcd(long a, long b)
    {
        if (a % b != 0)
        {
            return gcd(b, a % b);
        }
        else
        {
            return b;
        }
    }

    static long lcm(long a, long b)
    {
        return a * b / gcd(a, b);
    }
}