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

int main() {
    std::ios_base::sync_with_stdio(0);

    int p, d, m, s;
    cin >> p >> d >> m >> s;

    int n = 0;

    while(p > m && s > 0 && p <= s) {
        s -= p;
        p -= d;
        n++;
    }

    while(s >= m && s >= p) {
        n++;
        s -= m;
    } 

    cout << n << endl;
}