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 "fmt"

func main() {
	var a, b, c, d int
	fmt.Scan(&a, &b, &c, &d)
	a--
	fmt.Println((b-((b/c)+(b/d)-(b/lcm(c,d))))-(a-((a/c)+(a/d)-(a/lcm(c, d)))))
}

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

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