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: Accepted)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func parseInt(s string) (n int) {
	n, _ = strconv.Atoi(s)
	return
}

func gcd(a, b int) int {
	if b == 0 {
		return a
	}
	return gcd(b, a%b)
}

func lcm(a, b int) int {
	return (a * b) / gcd(a, b)
}

func main() {
	s := bufio.NewScanner(os.Stdin)
	s.Split(bufio.ScanWords)

	n := make([]int, 4)

	for i := range n {
		s.Scan()
		n[i] = parseInt(s.Text())
	}
	a := n[1] - (n[1] / n[2]) - (n[1] / n[3])
	b := n[0] - ((n[0] - 1) / n[2]) - ((n[0] - 1) / n[3])
	c := (n[1] / lcm(n[2], n[3]))
	d := ((n[0] - 1) / lcm(n[2], n[3]))
	ans := a - b + (c - d) + 1

	fmt.Println(ans)
}