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.Text;
using System.Collections.Generic;
using System.Linq;
using E = System.Linq.Enumerable;
 
class Program
 {
  
        static long[] a;
        static long N;
        static long K;
        
        static void Main(string[] args)
        {
          //入力を受け取る
          //long N = int.Parse(Console.ReadLine());
          long[] ABCD = Console.ReadLine().Split(' ').Select(x => long.Parse(x)).ToArray();
          long A = ABCD[0];
          long B = ABCD[1];
          long C = ABCD[2];
          long D = ABCD[3];
          long ans = C*D/gcd(C,D);
          
          //Console.WriteLine(ans);
          var multiC = B/C - (A-1)/C;
          var multiD = B/D - (A-1)/D;
          var multiCD = B/ans - (A-1)/ans;
          //Console.WriteLine(multiCD);
          long res = multiC+multiD-multiCD;
          
          Console.WriteLine((B-A+1)-res);
          
        }
  
  static long gcd(long a , long b){
    if(b>a){
      return gcd(b,a);
    }
    long ans = 1;
    while(b != 0){
      ans =b;
      b = a%b;
      a = b;
    }
    
    return ans;
  }
 }