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>
using namespace std;

long long GCD(long long x, long long y) {
	if (y == 0)return x;
	return GCD(y, x % y);
}

long long LCM(long long x, long long y) {
	return (x * y) / GCD(x, y);
}

long long f(int x, int y, long long a) {
	long long res = a;
	res-= a / x;
	res -= a / y;
	res += a / LCM(x, y);
	return res;
}

int main() {
	long long A, B;
	int C, D;
	cin >> A >> B >> C >> D;
	long long ans = f(C, D, B) - f(C, D, A - 1);
	cout << ans << endl;
	return 0;
}