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: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

class Program {
    static void Main (string[] args) {
          

        string[] str = Console.ReadLine ().Split(' ');
        long A = long.Parse(str[0]);
        long B = long.Parse(str[1]);
        long C = long.Parse(str[2]);
        long D = long.Parse(str[3]);
        
        double ra = System.Math.Ceiling((double)A / (double)C);
        double rb = System.Math.Ceiling((double)A / (double)D);

 

        long tmpA =0;
        long tmpB =0;
        List<long> ln = new List<long>();
        long i = (long)System.Math.Min(ra,rb);

        while(tmpA <= B && tmpB <= B){
            tmpA = C * i;
            tmpB = D * i;

            if(ln.IndexOf(tmpA)  < 0 && tmpA <= B){
                ln.Add(tmpA);
            }

            if(ln.IndexOf(tmpB) < 0 && tmpB <= B){
                ln.Add(tmpB);
            }

            i++;
        }

        long ans = B - A - ln.Count() + 1;
        
        Console.WriteLine(ans);
    }
}