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: Wrong Answer)

using System;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] a = (Console.ReadLine().Split(' '));
            //string[] a = ("314159265358979323 846264338327950288 419716939 937510582".Split(' '));
            long[] b = new long[4];

            for(int i=0;i < a.Length ; i++)
            {
                b[i] = long.Parse(a[i]);
            }
            if (b[0] == b[1])
            {
                if (b[0] % b[2] == 0 || b[0] % b[3] == 0)
                {
                    Console.Write("0");
                }
                Console.Write("1");
            }
            long al = b[2];
            long bl = b[3];
            long r = bl % al ;
            while(r!= 0)
            {
                bl = al;
                al = r;
                r = bl % al;
            }

            long basub = b[1] - b[0] + 1;
            long cdlcm = b[2] * b[3] / al;
            long cdiv = basub / b[2];
            long ddiv = basub / b[3];
            long cddiv = basub / cdlcm;
            long adjust = b[0] % b[2] > b[1] % b[2] ? 1 : 0;
            adjust += b[0] % b[3] > b[1] % b[3] ? 1 : 0;
            long adjustdiv = b[0] % cdlcm > b[1] % cdlcm ? 1 : 0;

            Console.Write(basub - (cdiv + ddiv -cddiv-adjustdiv+adjust));
        }
    }
}