#include <bits/stdc++.h>

#define x first
#define y second

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;

ostream& operator<<(ostream &out, const pii &a) { return out << '(' << a.x << ", " << a.y << ')'; }
istream& operator>>(istream &in, pii &a) { return in >> a.x >> a.y; }

const int INF = 2147483647;
const ll LLINF = 9223372036854775807LL;

// lambda-expression: [] (args) -> retType { body }

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	// cerr << boolalpha;
	(cout << fixed).precision(10);

	ll p, d, m, s;
	cin >> p >> d >> m >> s;

	ll ans = 0;
	bool bought;
	do {
		bought = s >= p;
		if (bought) {
			s -= p;
			p = max(p - d, m);
			ans++;
		}
	} while (bought);
	cout << ans << endl;
	return 0;
}