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;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Text;
using static System.Console;
using static System.Math;

namespace AtCodeeeer
{
    class AtCOOOOOOOOOOOder
    {
        static void Main(string[] args)
        {
            long[] s = ReadLine().Split(' ').Select(long.Parse).ToArray();

            long hoge = (s[1] / s[2]) - ((s[0]-1) / s[2]);
            long piyo = (s[1] / s[3]) - ((s[0]-1) / s[3]);
            long nan = Find(s[2], s[3], s[0] - 1);
            long tmp = (s[1] / nan) - ((s[0]-1) / nan);
            if (tmp < 0) tmp = 0;

            WriteLine((s[1] - (s[0]-1)) - ((hoge + piyo) - tmp) );
        }

        static long Find(long a,long b,long min)
        {
            long i = 1;
            while ((a*i) % b != 0 || (a*i) < min)
            {
                i++;
            }
            return a * i;
        }
    }
}