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;

namespace C___Anti_Division
{
    class Program
    {
        static void Main (string[] args)
        {
            var input = Console.ReadLine ().Split (' ');
            var a = long.Parse (input[0]);
            var b = long.Parse (input[1]);
            var c = long.Parse (input[2]);
            var d = long.Parse (input[3]);
            var max = Math.Max (c, d);
            var min = Math.Min (c, d);
            while (true)
            {
                var r = max % min;
                if (r == 0)
                    break;

                max = min;
                min = r;
            }
            var l = c * d / min;
            var e = b - b / c - b / d + b / l;
            var f = a - 1 - (a - 1) / c - (a - 1) / d + (a - 1) / l;
            Console.WriteLine (e - f);
        }
    }
}