#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    long long int ans=0;
    if(s<p)
        return 0;
    int x=p;
    int flag=0;
    while(s>=x)
    {
        s=s-x;
        ans++;
        if(flag==0)
        x=x-d;
        if(x<m)
        {
            flag=1;
            x=m;
        }
    }
    return ans;
    // Return the number of games you can buy
}

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;
}