#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int count = 0;
    int price = p;
    int money = s;
    while (price > m && money >= price) {
        ++count;
        money -= price;
        price -= d;
    }
    if (price < m)
        price = m;
    count += money / price;
    return count;
}

int main() {
    int p;
    int d;
    int m;
    int s;
    cin >> p >> d >> m >> s;
    int answer = howManyGames(p, d, m, s);
    cout << answer << endl;
    return 0;
}