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.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
public class ABC
{
    //          int[] split = Console.ReadLine().Split().Select(int.Parse).ToArray();

    public static void Main()
    {
        long[] split = Console.ReadLine().Split().Select(long.Parse).ToArray();
        long A, B, C, D;
        A = split[0];
        B = split[1];
        C = split[2];
        D = split[3];

        long GCD_C_D = gcd(C, D);
        long E = C * D / GCD_C_D;

        long benleft = n_canBeDividedUnderA(B, C) - n_canBeDividedUnderA(A - 1, C);
        long benright = n_canBeDividedUnderA(B, D) - n_canBeDividedUnderA(A - 1, D);

        long benboth = n_canBeDividedUnderA(B, E) - n_canBeDividedUnderA(A - 1, E);

        long output = B - A - benleft - benright + benboth + (long)1;
        Console.WriteLine(output);

    }

    public static long gcd(long A,long B)
    {
        if (A < B)
        {
            long temp = A;
            A = B;
            B = temp;
        }
        if (A % B == 0)
        {
            return B;
        }
        else
        {
            return gcd(B, A % B);
        }

    }
    public static long n_canBeDividedUnderA(long A, long div)
    {
        return A / div;
    }


    

}