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: Wrong Answer)

#include <bits/stdc++.h>
typedef long long ll;
using namespace std;

int sa(ll a, ll b) {
	if (a < b)
		swap(a, b);
	ll r = a % b;
	while (r != 0) {
		a = b;
		b = r;
		r = a % b;
	}
	return b;
}

int main() {
	ll a, b, c, d;
	cin >> a >> b >> c >> d;
	ll ans = 0;
	ans += b / c - (a - 1) / c;
	ans += b / d - (a - 1) / d;
	ans -= b / sa(c, d) - (a - 1) / sa(c, d);
	cout << b - a - ans + 1;
}