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: Time Limit Exceeded)

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

namespace AtCoder_1
{
    class Program
    {
        static void Main(string[] args)
        {
            //string s = Console.ReadLine();
            //int n = int.Parse(s.Split(' ')[0]);
            //int L = int.Parse(s.Split(' ')[1]);
            //List<int> nums = new List<int>();
            //for(int i = 1; i <= n; i++)
            //{
            //    nums.Add(L + i - 1);
            //}
            //int min = 1000;
            //foreach(int i in nums)
            //{
            //    min = (min < i) ? min : i;
            //}
            //nums.Remove(min);
            //int t = 0;
            //foreach(int i in nums)
            //{
            //    t += i;
            //}
            //Console.WriteLine(t);
            string s = Console.ReadLine();
            string[] ar = s.Split(' ');
            long c = 0;long d = 0;
            try
            {
               c = long.Parse(ar[2]);
                d = long.Parse(ar[3]);
            }
            catch { }
            long count = 0;
            for (long i = long.Parse(ar[0]);i <= long.Parse(ar[1]); i++)
            {
                try
                {
                    if (i % c != 0 && i % d != 0)
                    {
                        count++;
                    }
                }
                catch { }
            }
            Console.WriteLine(count);
        }
    }
}