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<bits/stdc++.h>

using namespace std;

long long gcf(long long a, long long b) {
	if (b == 0)
		return a;
	else
		return gcf(b, a % b);
}


int main() {

	// freopen("input.txt", "r", stdin);
	// freopen("output.txt", "w", stdout);

	long long a, b, c, d;
	cin >> a >> b >> c >> d;
	long long lcm = (c * d) / gcf(c, d);
	long long abc = ((b / c) - ceil((long double) a / c)) + 1;
	long long abd = ((b / d) - ceil((long double) a / d)) + 1;
	long long ablcm = ((b / lcm) - ceil((long double) a / lcm)) + 1;
	long long cnt = b - a + 1;
	cnt -= (abc + abd - ablcm);
	cout << cnt << '\n';
	return 0;
}