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 <iostream>
using namespace std;

int main()
{
    long long a, b, c, d, m, n, ans;
    cin >> a >> b >> c >> d;
    ans = b - (a - 1);
    if (c < d) {
        m = d;
        n = c;
    } else {
        m = c;
        n = d;
    }
    while (m % n != 0) {
        int a = n;
        n = m % n;
        m = a;
    }
        
    int lcm = c * d / n;
    ans -= (ans / c + ans / d) - (ans / lcm);
    cout << ans << endl;
    return 0;
}