abk1k2

/* Bogdan Iordache
 * O(logVMAX)
 */
#include <bits/stdc++.h>
using namespace std;

int main() {
#ifndef LOCAL
    ifstream cin("abk1k2.in");
    ofstream cout("abk1k2.out");
#endif
    int a, b, k1, k2;
    cin >> a >> b >> k1 >> k2;
    assert(1 <= a && a <= b && b <= 1000000000);
    assert(2 <= k1 <= k2 <= 1000000000);

    long long cnt_k1 = b / k1 - (a - 1) / k1;
    long long cnt_k2 = b / k2 - (a - 1) / k2;
    long long cnt = cnt_k1 * (cnt_k1 - 1) / 2 + cnt_k2 * (cnt_k2 - 1) / 2;

    long long cmmmc = 1LL * k1 * k2;
    while (k1) {
        int r = k2 % k1;
        k2 = k1;
        k1 = r;
    }
    cmmmc /= k2;

    long long cnt_cmmmc = b / cmmmc - (a - 1) / cmmmc;
    cnt -= cnt_cmmmc * (cnt_cmmmc - 1) / 2;

    cout << cnt << '\n';

    return 0;
}