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.IO;
using System.Collections.Generic;
namespace I_am_the_green_coder{
    class Inonoa{
        // なんか入力用の関数作ったけどまだテストしてないので使う前に確かめて
        static void Main(){
            string[] abcd = Console.ReadLine().Split();
            long a = long.Parse(abcd[0]);
            long b = long.Parse(abcd[1]);
            long c = long.Parse(abcd[2]);
            long d = long.Parse(abcd[3]);
            long mx = Math.Max(c,d);
            long mn = Math.Min(c,d);

            long kouyakusuu;

            mx = mx%mn;

            while(mx!=0 && mn!=0){
                mn = mn%mx;
                if(mn==0)break;
                mx = mx%mn;
            }

            kouyakusuu = Math.Max(mx,mn);

            long koubaisuu = c * d / kouyakusuu;


            long cmin = (a-1)/c; //1
            long dmin = (a-1)/d; //1
            long cmax = b/c; //4
            long dmax = b/d; //3
            long csa = cmax - cmin; //3
            long dsa = dmax - dmin; //2
            long cdmin = (a-1)/koubaisuu; //0
            long cdmax = b/koubaisuu; //1
            long cdsa = cdmax - cdmin; //1

            Console.WriteLine(b-a+1-csa-dsa+cdsa); //9-4-3-2+1
        }

        static readonly long MOD = 1000000007;


    }
}