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;
using System.Linq;

class prog{
	public static void Main(string[] args){
    	string[] input = Console.ReadLine().Split(' ');
      	long[] nums = new long[4];
      
      	for(int i = 0;i < 4;i ++){
        	nums[i] = long.Parse(input[i]);
        }
      
      	long A = nums[0];
      	long B = nums[1];
      	long C = nums[2];
      	long D = nums[3];
      
      	long count = B - A + 1;
      
      	count -= (B - A) / C + 1;
      	//Console.WriteLine(count);
      
      	count -= (B - A) / D + 1;
      	//Console.WriteLine(count);
      	
      	count += (B - A) / ((C*D)/gcd(C,D)) + 1;
      
      	Console.WriteLine(count);
    }
  
  	static long gcd(long a,long b){
    	if(a<b)return gcd(b,a);
      	while(b!=0){
        	long reminder = a % b;
          	a = b;
          	b = reminder;
        }
      	return a;
    }
}