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 C___Anti_Division
{
    class Program
    {
        static void Main(string[] args)
        {
            var A_B_C_D = Console.ReadLine().Split().Select(long.Parse).ToArray();
            long A = A_B_C_D[0], B = A_B_C_D[1], C = A_B_C_D[2], D = A_B_C_D[3];
            long E = Lcm(C, D);

            var cnt_C = B / C - Math.Ceiling((double)A / C) + 1;
            var cnt_D = B / D - Math.Ceiling((double)A / D) + 1;
            var cnt_E = B / E - Math.Ceiling((double)A / E) + 1;

            Console.WriteLine(B - A + 1 - (cnt_C + cnt_D - cnt_E));
        }

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

        static long Gcd(long a, long b)
        {
            if (a == 0) return b;
            if (b == 0) return a;

            return a > b ? GcdRecursive(a, b) : GcdRecursive(b, a);
        }

        static long GcdRecursive(long l, long r) => r == 0 ? l : GcdRecursive(r, l % r);
    }
}