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;

namespace app03
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] ABCD = Console.ReadLine().Split(' ');
            ulong A = ulong.Parse(ABCD[0]);
            ulong B = ulong.Parse(ABCD[1]);
            ulong C = ulong.Parse(ABCD[2]);
            ulong D = ulong.Parse(ABCD[3]);
            int count = 0;

            for(ulong i = A; i <= B; i++)
            {
                if( i % C == 0) {
                    continue;
                }
                if(i % D == 0)
                {
                    continue;
                }
                count++;
            }
            Console.WriteLine($"{count}");
        }
    }
}