#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 n;
    n=0;
    while(p>=m)
    {
        if(s>p)
        {
            s-=p;
            p-=d;
            n+=1;
        }
        else
        {
            break;
        }
    }
    if(p<(m+d))    n += s/m;
    return n;
}

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;
}