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;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
	class Program
	{
		static void Main(string[] args)
		{

			string[] values = Console.ReadLine().Split(' ');
			long a = long.Parse(values[0]);
			long b = long.Parse(values[1]);
			long c = long.Parse(values[2]);
			long d = long.Parse(values[3]);

			long m = Lcm(c, d);

			long divisible = b / c - (a - 1) / c + b / d - ( a - 1 ) / d - ( b / m - ( a - 1 ) / m );	

			long solution = b - (a - 1) - divisible;
		
			Console.WriteLine(solution.ToString());
				
		}



		public static long Lcm(long a, long b) {

			return (a * b )/ Gcd(a, b);

		}
		public  static long Gcd(long a, long b)
		{
			if (a < b)
			{
				Gcd(b, a);
			}
			while (b != 0)
			{
				long remeinder = a % b;
				a = b;
				b = remeinder;
			}

			return a;

	}
}