#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 remaining=s;
    int ans=0;
    int cost=p;
    while(remaining>=cost)
    {  if(cost>m&&remaining>=cost)
        {

            remaining=remaining-cost;
            cost=cost-d;
            ans++;
           
        }
        else{
           cost=m;
            if(remaining>=m)
            {
                while(remaining>=m)
                {
                    

                    remaining=remaining-m;
                    ans++;
                }

            }


        }


    }
   return ans;

}

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;
}