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;


namespace ConsoleApp11
{
    class Class76
    {
        static void Main()
        {
            ulong[] abcd = Console.ReadLine().Split().Select(ulong.Parse).ToArray();
            ulong count = abcd[1] - abcd[0] + 1;

            ulong divC = (abcd[1] / abcd[2]) - (abcd[0]-1) / abcd[2];
            ulong divD = (abcd[1] / abcd[3]) - (abcd[0]-1) / abcd[3];
            ulong divCD = abcd[1] / LCM(abcd[2],abcd[3]) - (abcd[0]-1) / LCM(abcd[2],abcd[3]);
            Console.WriteLine(count - divC - divD + divCD);
        }
        static ulong GCD(ulong a,ulong b)
        {
            return b == 0 ? a : GCD(b, a % b);
        }
        static ulong LCM(ulong a,ulong b)
        {
            return a*b / GCD(a, b);
        }
    }
}