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 ABC131C
{
    class MainClass
    {
        public static void Main(string[] args)
        {
            long[] abcd = Console.ReadLine().Split().Select(long.Parse).ToArray();
            
            long bCnt = abcd[1] - calc(abcd[1],abcd[2]) - calc(abcd[1], abcd[3]) + calc(abcd[1], Lcm(abcd[2], abcd[3]));
            long aCnt = abcd[0] - calc(abcd[0], abcd[2]) - calc(abcd[0], abcd[3]) + calc(abcd[0], Lcm(abcd[2], abcd[3]));

            Console.WriteLine(bCnt - aCnt);
        }

        public static long calc(long x, long y)
        {
            return (long)Math.Round((decimal)x / y);
        }

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

        public static long Gcd(long a, long b)
        {
            if (a < b) return Gcd(b, a);
            while (b != 0)
            {
                var temp = a % b;
                a = b;
                b = temp;
            }
            return a;
        }
    }
}