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>
#define rep(i, a, b) for(int i = a; i < b; i++)
#define Rep(i, a, b) for(int i = a; i <= b; i++)
#define _GLIBCXX_DEBUG
#define Vl vector<ll>
#define Vs vector<string>
#define ll long long
#define ALL(v) (v).begin(),(v).end()
using namespace std;

ll mod = 2019;

void solve() {
    ll a, b, c, d; cin >> a >> b >> c >> d;
    ll ans = b - a + 1;
    ll r1 = b/c, r2 = b/d;
    ll l1 = (a-1)/c, l2 = (a-1)/d;
    ll q = c*d;
    if(c%2 == 0 && d%2 == 0) q /= 2;
    ll r3 = b/q, l3 = (a-1)/q;
    ll m = (r1-l1)+(r2-l2)-(r3-l3);
    cout << ans - m << endl;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    solve();
    return 0;
}