CHIAHET C++

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

long long a, b, x, y;

long long gcd(long long a, long long b) {
    if (b == 0) return a;
    return gcd (b, a % b);
}

long long dem(long long x) {
    long long lef = a/x;
    if (a%x!=0) lef++;
    long long rig=b/x;
    return rig - lef + 1;
}

int main() {
    freopen ("CHIAHET.inp", "r", stdin);
    freopen ("CHIAHET.out", "w", stdout);

    cin >> a >> b >> x >> y;

    long long lcm = x * y / gcd(x, y);
    long long dx = dem(x);
    long long dy = dem(y);
    long long dlcm = dem(lcm);

    cout << dx + dy - dlcm << '\n';

    return 0;
}