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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
#include <map>
using namespace std;

long Gcd(long m, long n){
	long temp;
	while (m % n != 0){
		temp = n;
		n = m % n;
		m = temp;
	}
	return n;
}

int main(){
	long A, B, C, D;
	cin >> A >> B >> C >> D;
	long CD = C * D / Gcd(C, D);
	long A_C = A / C, A_D = A / D, A_CD = A / CD;
	long B_C = B / C, B_D = B / D, B_CD = B / CD;
	long Asum = A - A_C - A_D + A_CD;
	long Bsum = B - B_C - B_D + B_CD;
	long bit = 1;
	if(!(A % C) || !(A % D)) bit = 0;
	cout << Bsum - Asum + bit<< endl;
}