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 Java8 (OpenJDK 1.8.0) (judge verdict: Time Limit Exceeded)

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);

		long a = in.nextLong();
		long b = in.nextLong();
		long c = in.nextLong();
		long d = in.nextLong();
		long cnt = 0;
		long cd = c * d;

		// 頭の１行
		long head = 0;
		for ( long targ = 1; targ < a; targ++ ) {
			if ( targ % c != 0 && targ % d != 0 ) {
				head++;
			}
		}
		//System.out.println(head);

		long botomRight = b - (b % cd);
		//System.out.println(botomRight);
		long bodyCnt = botomRight * (cd - c - d + 1) / cd;
		//System.out.println(bodyCnt);
	
		for ( long targ = botomRight + 1; targ <= b; targ++ ) {
			if ( targ % c != 0 && targ % d != 0 ) {
				cnt++;
			}
		}
		//System.out.println(cnt);

		System.out.println(bodyCnt - head + cnt);
		in.close();
	}
}