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 Go (1.6) (judge verdict: Wrong Answer)

package main

import (
	"fmt"
)

func main() {
	var a, b, c, d int
	fmt.Scanf("%d %d %d %d", &a, &b, &c, &d)

	a--
	n := b - a

	C := b/c - a/c
	D := b/d - a/d

	l := a * b / gcb(a, b)

	ans := n - (C + D - l)
	fmt.Print(ans)
}

func gcb(c, d int) int {
	if c == 0 {
		return d
	} else if d == 0 {
		return c
	}
	return gcb(d, c%d)
}