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 System.Text;

namespace ProgramingStudying2
{
    class Program
    {
        static void Main(string[] args)
        {
            var abcd = Console.ReadLine().Split();
            var a = long.Parse(abcd[0]);
            var b = long.Parse(abcd[1]);
            var c = long.Parse(abcd[2]);
            var d = long.Parse(abcd[3]);

            long gcd(long c, long d)
            {
                if(c % d == 0)
                {
                    return d;
                }
                else
                {
                    return gcd(d, c % d);
                }
            }

            var lcm = c * d / gcd(c, d);

            var cDiv = b / c - (a - 1) / c;
            var dDiv = b / d - (a - 1) / d;
            var lcmDiv = b / lcm - (a - 1) / lcm;

            Console.WriteLine(b - a + 1 - cDiv - dDiv + lcmDiv);
        }
    }
}