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 main() {

	var a,b,c,d int
	fmt.Scan(&a, &b, &c, &d)

	ans := f(b, c, d) - f(a-1, c, d)
	fmt.Println(ans)

}

func f(x, c, d int) int {
	res := x
	res -= x/c
	res -= x/d
	res += x/lcm(c,d)
	return res
}

func gcd(a, b int) int {
	if a > b {
		return gcd(b, a)
	}
	for a != 0 {
		a, b = b % a, a
	}
	return b
}
func lcm(a, b int) int {
	return a * b / gcd(a, b)
}