#include<bits/stdc++.h>
#define maxn 50

using namespace std;

int p, n, m, s;

int main()
{
    int res = 0;
    cin >> p >> n >> m >> s;
    while(s >= p)
    {
        res++;
        s -= p;
        if(p - n <= m) p=m;
        else p -= n;
    }
    cout << res;
}