#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;
    for ( ; s > 0 && p-d*count > m; ++count)
        s -= (p-d*count);
    for ( ; s >= 0; ++count)
        s -= m;
    return count-1;
}

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;
}