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]);
        int C = int.Parse(str[2]);
        int D = int.Parse(str[3]);
        
        int tmpC = (int)(System.Math.Floor((double)B / C) - System.Math.Ceiling((double)A / C));
        int tmpD = (int)(System.Math.Floor((double)B / D) - System.Math.Ceiling((double)A / D));

        
        long E = System.Math.Abs(Lcm(C,D));
        int common =  (int)(B/ E - A / E);

        long ans = B - A - (tmpC + tmpD - common) -1;

        Console.WriteLine(ans);
    }
         public static long Gcd(long a, long b) {
         if (a < b)
             // 引数を入替えて自分を呼び出す
             return Gcd(b, a);
         while (b != 0) {
             var remainder = a % b;
             a = b;
             b = remainder;
         }
         return a;
     }
            public static long Lcm(long a, long b) {
            return a * b / Gcd(a, b);
        }
}