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;

public static partial class Program
{
    public static void Main()
    {
        var abcd = CRL().ArrayLongs();
        var a = abcd[0];
        var b = abcd[1];
        var c = abcd[2];
        var d = abcd[3];

        var cnt = b - a + 1;

        var cLim = b / c - a / c;
        var dLim = b / d - a / d;

        var cLimMulD = cLim / d;

        var ret = cnt - (cLim + dLim - cLimMulD);
        if (b.IsEven())
        {
            ret++;
        }

        Console.WriteLine(ret);
    }
}

public static partial class Program
{
    //テンプレここから
    public static int Sigma(int n, int next = 1, int val = 0) => next > n ? val : Sigma(n, next + 1, val + next);
    public static long GCD(long a, long b) => b == 0 ? a : GCD(b, a % b);
    public static int GCD(int a, int b) => b == 0 ? a : GCD(b, a % b);
    public static long LCM(long a, long b) => a * b / GCD(a, b);
    public static int LCM(int a, int b) => a * b / GCD(a, b);
    public static string CRL() => Console.ReadLine();
    public static void CWL(object obj) => Console.WriteLine(obj);
    public static int ToInt(this double d) => (int) d;
    public static long ToLong(this double d) => (long) d;
    public static int ToInt(this string str) => int.Parse(str);
    public static long ToLong(this string str) => long.Parse(str);
    public static long[] ToLong(this IEnumerable<string> strs) => strs.Select(x => x.ToLong()).ToArray();
    public static int[] ToInt(this IEnumerable<string> strs) => strs.Select(x => x.ToInt()).ToArray();
    public static long[] ArrayLongs(this string str, char opr = ' ') => str.Split(opr).ToLong();
    public static int[] ArrayInts(this string str, char opr = ' ') => str.Split(opr).ToInt();
    public static long Diff(long a, long b) => Math.Abs(Math.Max(a, b) - Math.Min(a, b));
    public static int Diff(int a, int b) => Math.Abs(Math.Max(a, b) - Math.Min(a, b));
    public static long Sign(this long i) => Math.Sign(i);
    public static bool IsEven(this long i) => i % 2 == 0;
    public static bool IsEven(this int i) => i % 2 == 0;
    public static readonly int[] Dx = {0, -1, 0, 1};
    public static readonly int[] Dy = {-1, 0, 1, 0};
    public const int Mod = 1000000007;
    public static string alphabet = "abcdefghijklmnopqrstuvwxyz";
    public static long ToLong(this char c) => c.ToString().ToLong();
    public static int ToInt(this char c) => c.ToString().ToInt();
    public static long[] Sort(this long[] array) => array.OrderBy(x => x).ToArray();
    public static int[] Sort(this int[] array) => array.OrderBy(x => x).ToArray();
    public static long[] DSort(this long[] array) => array.OrderByDescending(x => x).ToArray();
    public static int[] DSort(this int[] array) => array.OrderByDescending(x => x).ToArray();
    public static string Join(this IEnumerable<string> array, string sep = "") => string.Join(sep, array);
    public static string Join(this IEnumerable<char> array, string sep = "") => string.Join(sep, array);

    public static string JoinToStr(this IEnumerable<int> array, string sep = "")
        => array.Select(x => x.ToString()).Join(sep);

    //テンプレここまで
}