#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 i,cnt=0;
    while((s-p)>=0)
    {
         s=s-p;
        if((p-d)>m)
            p=p-d;
        else
            p=m;
        cnt++;
       
        //cout<<"\n"<<p<<"  "<<s;
        
    }
    return cnt;
}

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;
}