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.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp5
{

    class Program
    {
        static void Main(string[] args)
        {

            String S = Console.ReadLine();
            String[] line = S.Split(' ');
            long A = long.Parse(line[0]);
            long B = long.Parse(line[1]);
            long C = long.Parse(line[2]);
            long D = long.Parse(line[3]);

            if(C > D)
            {
                long tmp = C;
                C = D;
                D = tmp;
            }

            long X = C * D;
            long C1 = C;
            long D1 = D;
            long r = C % D;

            while(r != 0)
            {
                C1 = D1;
                D1 = r;
                r = C1 % D1;
            }

            X = X / D1;
            int f = 0;

            long C2 = B / C - A / C;
            long D2 = B / D - A / D;
            long X2 = B / X - A / X;

            if(A % C != 0 && A % D != 0)
            {
                f = 1;
            }

            Console.WriteLine((B - A) - (C2 + D2 - X2) + f);

        }



    }
}