#include <bits/stdc++.h>

using namespace std;

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

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;
}