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.Collections.Generic;
using System.Linq;
using System.Text;

public class MainClass
{
	public static void Main(string[] args)
	{
		string[] s = Input();
		long a = long.Parse(s[0]);
		long b = long.Parse(s[1]);
		long c = long.Parse(s[2]);
		long d = long.Parse(s[3]);
		
		if(c==1||d==1)
		{
			Console.WriteLine(0);
			return;
		}
		long sc = A(a,b,c);
		long sd = A(a,b,d);
		long se = A(a,b,c*d);
		
		//Console.WriteLine("{0} {1} {2}", sc, sd, se);
		Console.WriteLine(sc+sd-se);
	}

	public static long A(long a, long b, long c)
	{
		long souwa = 0;
		if(a%c!=0)
		{
			long s = a/c+1;
			long m = b/c;
			souwa += (m-s)*(c-1);
			souwa+=s*c-a;
			//Console.WriteLine("m:{0} - {1} / {2}", s, m, (s*c-a));
		}
		else
		{
			long s = a/c;
			long m = b/c;
			souwa += (m-s)*(c-1);
			//Console.WriteLine("m:{0} - {1}", s, m);
		}
		long k = b%c;
		return souwa + k;
	}
	
	public static string[] Input()
	{
		return Console.ReadLine().Split(' ');
	}

	
	public static int Clamp(int val, int max, int min = 0)
	{
		return Math.Min(max, Math.Max(min, val));
	}

	
}