#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int p, d, m, s;
    cin >> p >> d >> m >> s;
    int ans = 0;
    while (s > 0) {
        s -= max (p, m);
        p -= d;
        ++ans;
    }
    if (s < 0)   --ans;
    cout << ans << endl;
    return 0;
}