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 (1.14.1) (judge verdict: Accepted)

package main

import "fmt"

func Foo(a, b int) int {
	x := a * b
	if a < b {
		tmp := a
		a = b
		b = tmp
	}
	r := a % b
	for r != 0 {
		a = b
		b = r
		r = a % b
	}
	return x / b
}

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

	cd := Foo(c, d)

	cleft := a
	dleft := a
	cdleft := a

	ans := b - a + 1

	if cleft%c != 0 {
		cleft = int(a/c)*c + c
	}
	if dleft%d != 0 {
		dleft = int(a/d)*d + d
	} else {
	}
	if cdleft%cd != 0 {
		cdleft = int(a/cd)*cd + cd
	}

	var ccnt, dcnt, cdcnt int

	if cleft <= b {
		ccnt = ((b - cleft) / c) + 1
	}
	if dleft <= b {
		dcnt = ((b - dleft) / d) + 1
	}
	if cdleft <= b {
		cdcnt = ((b - cdleft) / cd) + 1
	}

	ans = ans - (ccnt + dcnt - cdcnt)

	fmt.Println(ans)
}