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.Linq;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            
            long[] Array = Console.ReadLine().Split(' ').Select(i => long.Parse(i)).ToArray();
            long A = Array[0];
            long B = Array[1];
            long C = Array[2];
            long D = Array[3];
            
            long AC = A / C;
            if (A % C != 0)
            {
                AC += 1;
            }
            long BC = (B / C) + 1;
            
            long AD = (A / D);
            if (A % D != 0)
            {
                AD += 1;
            }
            long BD = (B / D) + 1;

            long gcd = Lcm(C, D);
            long ACD = A / gcd;
            if (A % gcd != 0)
            {
                ACD += 1;
            }
            long BCD = B / gcd;
            if (B % gcd != 0)
            {
                BCD += 1;
            }
            Console.WriteLine((B - A + 1) - ((BC - AC) + (BD - AD) - (BCD - ACD)));
        }

        public static long Lcm(long a, long b)
        {
            return a * b / Gcd(a, b);
        }

        // ユークリッドの互除法 
        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;
        }
    }
}