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 Kotlin (1.3.71) (judge verdict: Accepted)

import java.io.BufferedReader
import java.io.InputStream
import java.io.InputStreamReader
import java.io.PrintWriter
import java.lang.IllegalArgumentException
import java.lang.StringBuilder
import java.lang.reflect.Modifier
import java.util.*

fun lcm(a:Long, b:Long):Long {
    return a / gcd(a, b) * b
}

fun gcd(a:Long, b:Long):Long {
    val c = a % b
    if (c == 0L) return b
    return gcd(b, c)
}

fun PrintWriter.solve(sc: FastScanner) {
    val a = sc.nextLong()
    val b = sc.nextLong()
    val c = sc.nextLong()
    val d = sc.nextLong()
    println(calc(b, c, d) - calc(a - 1, c, d))
}

fun calc(b:Long, c:Long, d:Long):Long {
    return b - b / c - b / d + b / lcm(c, d)
}

fun main() {
    val writer = PrintWriter(System.out, false)
    writer.solve(FastScanner(System.`in`))
    writer.flush()
}

class FastScanner(s: InputStream) {
    private var st = StringTokenizer("")
    private val br = BufferedReader(InputStreamReader(s))

    fun next(): String {
        while (!st.hasMoreTokens()) st = StringTokenizer(br.readLine())

        return st.nextToken()
    }

    fun nextInt() = next().toInt()
    fun nextLong() = next().toLong()
    fun nextLine() = br.readLine()
    fun nextDouble() = next().toDouble()
    fun ready() = br.ready()
}