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;

namespace MyProgram{
    class AtCoder{
        static void Main(string[] args){
            long[] input = Array.ConvertAll(Console.ReadLine().Split(' '),long.Parse);
            long A = input[0];
            long B = input[1];
            long C = input[2];
            long D = input[3];
            long gcd = C*D/Gcd(C,D);
            Console.WriteLine(B-A+1 - (B/C - (A-1)/C + B/D - (A-1)/D - (B/gcd-A/gcd)));     
        }

        static long Gcd(long m,long n){
            long temp;
            while(m%n!=0){
                temp =n;
                n = m%n;
                m = temp;
            }
            return n;
        }
    }
}