#include <bits/stdc++.h>
	#define MOD							1000000007
	#define rep(var, initVal, upto)		for(int var = initVal; var<upto; ++var)
	#define repi(var, initVal, upto)	for(int var = initVal; var>=upto; --var)
	#define inArr(A,n)					rep(i, 0, n)  cin >> A[i];
	#define inArr2d(A, n, m)			rep(i, 0, n) rep(j, 0, m)   cin >> A[i][j];
	#define pd1(a)						cout << #a << " : " << a << endl;
	#define pd2(a, b)					cout << #a << " : " << a << " " << #b << " : " << b << endl;
	#define pdArr(A, n)					rep(i, 0, n) cout << A[i] << " "; cout << endl;
	#define pdArr2d(A, n, m)			rep(i, 0, n) { rep(j, 0, m) cout << A[i][j] << " "; cout << endl; }
	#define psep						cout << "-------------------------------" << endl;
	#define pbsep 						cout << "===============================" << endl;
	#define pbbsep						cout << "###############################" << endl;
	#define MAX(a, b)					((a)>(b)?(a):(b))
	#define MIN(a, b)					((a)<(b)?(a):(b))
	#define all(x)						x.begin(), x.end()
	#define IO							cout << boolalpha;ios_base::sync_with_stdio(false);cin.tie(NULL);
	using namespace std;

	typedef long long					l;
	typedef unsigned long long			ul;

	typedef vector<int>					vi;
	typedef vector<char>				vc;
	typedef vector<bool>				vb;
	typedef vector<string>				vs;
	typedef vector<double>				vd;
	typedef vector<l>					vl;
	typedef vector<ul>					vul;
	typedef vector<vi>					vvi;
	typedef vector<vl>					vvl;
	typedef vector<vul>					vvul;
	typedef vector<vb>					vvb;
	typedef vector<vc>					vvc;

	typedef pair<int, int>				ii;
	typedef pair<l, l>					ll;
	typedef pair<double, double>		dd;

	typedef vector<ii>					vii;
	typedef vector<ll>					vll;
	typedef vector<dd>					vdd;

	template<class T> inline void Swap(T &a, T &b){ a ^= b; b ^= a; a ^= b; }

	l exp(l a, ul b, ul mod){
		l res = 1;
		while(b){   if(b&1) res = (res*a)%mod;   a = (a*a)%mod; b >>= 1;    }
		return res%mod;
	}

	l modInverse(l a, ul m) { return exp(a, m - 2, m); }

int main(){
	IO;

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

	int count = 0;
	while(p > m){
		s -= p;
		p -= d;
		if(s >= 0)
			++count;
	}

	while(s > 0){
		s -= m;
		if(s >= 0)
			++count;
	}

	cout << count << endl;

	return 0;
}