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;
class AntiDiv{
	static void Main(string[] args){
		string[] ABCD = Console.ReadLine().Split(' ');
		long A = long.Parse(ABCD[0]);
		long B = long.Parse(ABCD[1]);
		long C = long.Parse(ABCD[2]);
		long D = long.Parse(ABCD[3]);
		long AntiDiv = (B - A + 1) - BetDiv(A,B,C) - BetDiv(A,B,D) + BetDiv(A,B,LCM(C,D));
		Console.WriteLine(AntiDiv);
	}
	static long BetDiv(long A,long B,long C){
		return (B / C) - ((A - 1) / C);
	}
	static long GCD(long A,long B){
		if((A % B) == 0)return B;
		else return GCD(B,A % B);
	}
	static long LCM(long A,long B){
		return A * B / GCD(A,B);
	}
}