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 ll = long long;
using namespace std;


ll count_number(ll A, ll B, ll d)
{
    ll res;
    res = B / d - A / d;
    if (A % d == 0)
        res++;
    return res;
}

ll gcd(ll a, ll b)
{
    ll big = max(a, b);
    ll mini = min(a, b);
    ll res = big % mini;
    while (res != 0)
    {
        big = mini;
        mini = res;

        res = big % mini;
    }
    return mini;
}
int main()
{
    ll A, B, C, D;
    cin >> A >> B >> C >> D;
    ll ans = 0;
    ll common = C * D / gcd(C, D);

    ans = count_number(A, B, C) + count_number(A, B, D) - count_number(A, B, common);
    // cout << count_number(A, B, C)  << endl;
    // cout << count_number(A, B, D)  << endl;
    // cout << count_number(A, B, C * D)  << endl;

    ans = B - A + 1 - ans;
    
    cout << ans << endl;
    return 0;
}