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

func out(x ...interface{}) {
	fmt.Println(x...)
}

var sc = bufio.NewScanner(os.Stdin)

func getInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func getString() string {
	sc.Scan()
	return sc.Text()
}

// min, max, asub, absなど基本関数
func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func asub(a, b int) int {
	if a > b {
		return a - b
	}
	return b - a
}

func abs(a int) int {
	if a >= 0 {
		return a
	}
	return -a
}

// GCD : greatest common divisor (GCD) via Euclidean algorithm
func GCD(a, b int) int {
	for b != 0 {
		t := b
		b = a % b
		a = t
	}
	return a
}

// LCM : find Least Common Multiple (LCM) via GCD
func LCM(a, b int, integers ...int) int {
	result := a / GCD(a, b) * b

	for i := 0; i < len(integers); i++ {
		result = LCM(result, integers[i])
	}

	return result
}

func main() {
	sc.Split(bufio.ScanWords)

	A, B, C, D := getInt(), getInt(), getInt(), getInt()

	lcm := LCM(C, D)
	t := B / lcm
	f := A / lcm
	tc := B / C
	fc := A / C
	td := B / D
	fd := A / D

	// out(lcm)
	ans := B - A + 1
	// out(ans, t, f, ",", tc, fc, ",", td, fd)
	ans -= tc - fc
	if A%C == 0 {
		ans--
	}
	ans -= td - fd
	if A%D == 0 {
		ans--
	}
	ans += t - f
	if A%lcm == 0 {
		ans--
	}

	out(ans)
}