#include <bits/stdc++.h>

using namespace std;

int main() {
    int p;
    int d;
    int m;
    int s,k,c=0,price;
    cin >> p >> d >> m >> s;
    k = s;
    while(k>0)
    {
        if(p>s)
        {   cout<<c;
             exit(0);
        }
        else
        {
            if(c == 0)
            {
                k = k - p;
                c++;
                price = p;
            }
            else if(price - d >= m)
            {
                k = k - (price - d);
                if(k<0)
                    break;
                c++;
                price = price - d;
            }
            else
            {
                k = k - (m);
                if(k < 0)
                    break;
                c++;
            }
        }
    }
    cout<<c;
    return 0;
}