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.Text;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
class Program
{
	static void Main(string[] args)
	{
		string[] input = Console.ReadLine().Split(' ');
		ulong A = ulong.Parse(input[0]);
		ulong B = ulong.Parse(input[1]);
		ulong C = ulong.Parse(input[2]);
		ulong D = ulong.Parse(input[3]);
		
		ulong CD = C * D;
		
		ulong[] ans = new ulong[6];
		ans[0] = B / C - (A - 1) / C;
		ans[1] = B / D - (A - 1) / D;
		ans[2] = B / CD - (A - 1) / CD;
		Console.WriteLine(B - A + 1 - ans[0] - ans[1] + ans[2]);
	}
}