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

typedef long long ll;

ll f(int a, int b) {
    ll ans = 0;
    for (int i = 1; i <= a / i && i <= b - i; i++) {
        ans += min(a / i, b - i) - i + 1;
    }
    return ans;
}
int main() {
    #define task "hall"
    freopen(task".in", "r", stdin);
    freopen(task".out", "w", stdout);
    ll a, b, c, d;
    cin >> a >> b >> c >> d;
    c = (c + 1) / 2;
    d = d / 2;
    a--;
    c--;
    cout << f(b, d) - f(b, c) - f(a, d) + f(a, c) << endl;
    return 0;
}