#include <bits/stdc++.h>
using namespace std;
int main() {
    int p;
    int d;
    int m;
    int s,i,t=0,c=0;
    cin >> p >> d >> m >> s;
    while(t<=s)
    {
        if(p>m)
        {
            t=t+p;
            p=p-d;
            c++;
        }
        else
        {
            t=t+m;
            c++;
        }
    }
    cout<<c-1;
}