#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
int main()
{
    std::ios_base::sync_with_stdio(0);
    int p, d, m, s, i = 0;
    cin >> p >> d >> m >> s;
    int ans = 0;
    while (p > m && s > 0 && p<=s)
    {
        ans++;
        s -= p;
        p -= d;
    }
    while (s >= m && s>=p)
    {
        ans++;
        s -= m;
    }
    cout << ans << endl;
    return 0;
}