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

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;
}