#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 numGames = 0;
    while(s >= p && p >= m)
    {
        numGames++;
        s -= p;
        p -= d;
    }
    if(s >= p)
        numGames += s/m;
    return numGames;
}

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;
}