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;

namespace C_ABC131
{
    class MainClass
    {

        static long[] s;

        public static void Main(string[] args)
        {
            s = Array.ConvertAll(Console.ReadLine().Split().ToArray(), long.Parse);
            long c = s[1] / s[2];
            c -= (s[0] - 1) / s[2];
            long d = s[1] / s[3];
            d -= (s[0] - 1) / s[3];
            long gcd = Koubai(s[2], s[3]);
            long katsu = s[1] / gcd;
            katsu -= (s[0] - 1) / gcd;

            long ans = s[1] - s[0] + 1 - c - d + katsu;

            //Console.WriteLine("c:{0} d:{1} katsu:{2} gcd:{3}", c, d, katsu, gcd);

            Console.WriteLine(ans);



        }

        public static long Koubai(long a, long b)
        {
            long tmp;
            // a<bにする
            if (a >= b)
            {
                tmp = a;
                a = b;
                b = tmp;
            }
            long x = a * b;

            long r = b % a;
            while (r != 0)
            {
                b = a;
                a = r;
                r = b % a;
            }
            return x / a;

        }
    }


}