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.Linq;

public class Test
{
	public static void Main()
	{
		// your code goes here
		
		var z = Console.ReadLine().Split().Select(x => long.Parse(x)).ToArray();
		long atcoder = 1000000007;
		long a = z[0];
		long b = z[1];
		long c = z[2];
		long d = z[3];
		long e = b/c+2;
		long f = a/c-2;
		long g = b/d+2;
		long h = a/d-2;
		long k = c*d;
		long l = b/k+2;
		long m = a/k-2;
		long counter = b-a+1;
		
		for(long i=e; i!=f; i--){
			if(b>=c*i){
				if(a<=c*i){
					counter--;
				}
			}
		}
		
		for(long j=g; j!=h; j--){
			if(b>=d*j){
				if(a<=d*j){
					counter--;
				}
			}
		}
		
		for(long n=l; n!=m; n--){
			if(b>=k*n){
				if(a<=k*n){
					counter++;
				}
			}
		}
		
		Console.WriteLine(counter);
		
	}
}