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;

namespace ABC131
{
    class C
    {
        static void Main(string[] args)
        {
            string[] input = Console.ReadLine().Split(' ');
            long a = long.Parse(input[0]);
            long b = long.Parse(input[1]);
            long c = long.Parse(input[2]);
            long d = long.Parse(input[3]);

            long lcm = (c * d) / CalGcd(c, d);

            long res = (b - a + 1) - (b / c - (a - 1) / c) - (b / d - (a - 1) / d) + (b / lcm - (a - 1) / lcm);

            Console.WriteLine(res);

        }

        static long CalGcd(long a, long b)
        {
            if (b == 0) { return a; }
            return CalGcd(b, a % b);
        }
    }
}