#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
    int count = 0;
    while (s >= 0)
    {
        s = s - p;
        if ((p - d) > m)
            p = p - d;
        else
            p = m;
        count++;
    }
    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;
}