#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    // Return the number of games you can buy
    if (s < p)
        return 0;
    int count = 0;
    while (s > 0)
    {
        if (p == m)
        {
            if (s-p < 0)
                break;
            s-=p;
            count++;
            cerr << "s:" << s << std::endl;
        }
        if (p - d < m)
        {
            s-=p;
            int discout = p - m;
            p -= discout;
            cerr << "pdiscount:" << p << std::endl;
            
            cerr << "s:" << s << std::endl;
            count++;
        }
        else
        {
            s-=p;
            p-=d;
           
            cerr << "p" << p << std::endl;
            cerr << "s:" << s << std::endl;
            count++;
        }
    }
    if (s < 0)
        count--;
    return count;
}

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;
}