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)

// C - Anti-Division
//20190913

using System;
using System.Linq;

namespace C
{
    class Program
    {
        static void Main(string[] args)
        {
            long[] abcd = Console.ReadLine().Split().Select(long.Parse).ToArray();
            long a = abcd[0];
            long b = abcd[1];
            int c = (int)abcd[2];
            int d = (int)abcd[3];

            long ans = b-a;

            long numOfMultipleC = (long) ((int) (b-a) / c);
            long numOfMultipleD = (long) ((int) (b-a) / d);
            
            long leastCommonMultipleCD = LeastCommonMultiple(c,d);
            long numOfMultipleCD = (long)(int) (b-a) / leastCommonMultipleCD;

            ans = ans - numOfMultipleC - numOfMultipleD + numOfMultipleCD;

            Console.WriteLine(ans);

        }

        static long LeastCommonMultiple(long m,long n)
        {
            
            return m*n / GCD(m,n);
        }
        
        static long GCD(long m,long n)
        {
            while(m%n != 0)
            {
                long temp = n;
                n = m%n;
                m = temp;
            }
            return n;
        }
    }
}