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 AtCoder.ABC._131
{
    class c
    {
        static void Main(string[] args)
        {
            var line = Console.ReadLine().Trim();
            var spl = line.Split(' ');
            var A = long.Parse(spl[0]) - 1;
            var B = long.Parse(spl[1]);
            var C = long.Parse(spl[2]);
            var D = long.Parse(spl[3]);
            var CD = C * D / gcd(C, D);
            var cnt = B - A;
            var divCnt = B / C - A / C + B / D - A / D - (B / CD - A / CD);
            Console.WriteLine(cnt - divCnt);
        }

        static long gcd(long i, long j)
        {
            if(i < j)
            {
                return gcd(j, i);
            }
            while(j != 0)
            {
                var t = i % j;
                i = j;
                j = t;
            }
            return i;
        }
    }
}