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 Program
{
    static void Main(string[] args)
    {
        var abcd = Console.ReadLine().Split();
        var a = long.Parse(abcd[0]) - 1;
        var b = long.Parse(abcd[1]);
        var c = long.Parse(abcd[2]);
        var d = long.Parse(abcd[3]);
        var e = lcm(c, d);

        var ax = a - a / c;
        var ay = a - a / d;
        var az = a - a / e;

        var bx = b - b / c;
        var by = b - b / d;
        var bz = b - b / e;

        var A = ax + ay - az;
        var B = bx + by - bz;

        var ans = B - A;
        Console.WriteLine(ans);
    }

    static long gcd(long x, long y)
    {
        return x == 0 ? y : gcd(y % x, x);
    }

    static long lcm(long x, long y)
    {
        return x * y / gcd(x, y);
    }
}