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 (
	"fmt"
)

func main() {
	var a, b, c, d int
	fmt.Scan(&a, &b, &c, &d)
	if a != b {
		if c != d {
			cResult := calcCount(a, b, c)
			dResult := calcCount(a, b, d)
			var cdResult int
			cdResult = calcCount(a, b, lcm(c, d))

			res := cResult + dResult - cdResult
			fmt.Println(b - a + 1 - res)
		} else {
			fmt.Println(b - a + 1 - calcCount(a, b, c))
		}
	} else {
		if a%c == 0 {
			fmt.Println(0)
		} else if a%d == 0 {
			fmt.Println(0)
		} else {
			fmt.Println(1)
		}
	}

}

func calcCount(head int, tail int, num int) int {
	headMod := head % num
	if headMod != 0 {
		headMod = num - headMod
	}
	tailMod := tail % num
	store := tail - head + 1 - tailMod - headMod
	if store <= 0 {
		store = 0
	}
	res := store/num + 1
	return res
}

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

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