#include <bits/stdc++.h>
#include <math.h>
using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int res=0;
    while(p>=m && s>=0){
        s=s-p;
        p=p-d;
        if(s<=0){
            break;
        }
        res++;
        //cout<<p<<" "<<d<<" "<<s<<" "<<res<<"\n";
    }
    while(s>=m){
        res++;
        s=s-m;
    }
 
    return res;
}

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;
}