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: Accepted)

using System;
class c
{
    static void Main()
    {
        var inp = Array.ConvertAll(Console.ReadLine().Split(), long.Parse);
        long a = inp[0], b = inp[1], c = inp[2], d = inp[3];
        a = a - 1;
        long x = LCM(c, d);
        long before = DIV(a, c) + DIV(a, d) - DIV(a, x);
        long after = DIV(b, c) + DIV(b, d) - DIV(b, x);
        Console.WriteLine(after - before);
    }
    public static long DIV(long a, long b)
    {
        return a - a / b;
    }
    public static long GCD(long a, long b)
    {
        if (a > b) return GCD(b, a);
        while (a != 0)
        {
            long temp = b % a;
            b = a;
            a = temp;
        }
        return b;
    }
    public static long LCM(long a, long b)
    {
        return a * b / GCD(a, b);
    }

}