#include <bits/stdc++.h>

using namespace std;

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

}

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;
}