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: Time Limit Exceeded)

package main

import (
	"fmt"
)

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

	cStart := 0
	cEnd := 0
	cNum := 0
	if c > b {
		cNum = 0
	} else {
		for i := 0; ; i++ {
			if cStart == 0 && c*i >= a {
				cStart = i
			}
			if c*i > b {
				cEnd = i - 1
				break
			}
		}
		cNum = cEnd - cStart + 1
	}

	dStart := 0
	dEnd := 0
	dNum := 0

	if d > b {

	} else {
		for i := 0; ; i++ {
			if dStart == 0 && d*i >= a {
				dStart = i
			}
			if d*i > b {
				dEnd = i - 1
				break
			}
		}
		dNum = dEnd - dStart + 1
	}

	cdNum := 0
	if cNum > 0 && dNum > 0 {

		minCommonMultiple := c * d / getMinCommonDivisor(c, d)
		if minCommonMultiple <= b {

			cdStart := 0
			cdEnd := 0
			for i := 0; ; i++ {
				if cdStart == 0 && minCommonMultiple*i >= a {
					cdStart = i
				}
				if minCommonMultiple*i > b {
					cdEnd = i - 1
					break
				}
			}

			cdNum = cdEnd - cdStart + 1
		}

	}
	// fmt.Println(c * d / getMinCommonDivisor(c, d))
	// fmt.Println(cNum, dNum, cdNum)
	res := b - a + 1 - (cNum + dNum - cdNum)
	fmt.Println(res)
}

func getMinCommonDivisor(m, n int) int {
	for m%n != 0 {
		temp := n
		n = m % n
		m = temp
	}
	return n
}