#include<bits/stdc++.h>
#define fri(i,n) for(int i=0;i<n;i++)
#define fr(i,a,b) for(int i=a;i<=b;i++)
#define ol(v) v.begin(),v.end()
#define forc(v) for(auto it:v)
#define se second
#define fi first
#define pb push_back
#define pf push_front
#define MX 1e18
#define MN -MX
#define MOD 1000000007

using namespace std;
typedef long long ll;
typedef long double ld;

template <typename T> istream&operator>>(istream &inp, vector<T> &vec){
	fri(i,vec.size()) inp>>vec[i];
	return inp;
}

template <typename T> ostream&operator<<(ostream &oup, vector<T> vec){
	forc(vec) oup<<it<<" ";
	oup<<"\n";
	return oup;
}


int main(){
	ios::sync_with_stdio(false);
	#ifdef DBG
		freopen("in", "r", stdin);
	#endif

	int p, d, m, s, ans = 0;

	cin>>p>>d>>m>>s;
	int i = 0, lst = p;
	for(i=0;;i++){
		if(!i){
			if(s >= p) s-=p;
			else {i = 0; break;}
			lst -= d;
			continue;
		}

		if(lst > m){
			if(s-lst < 0) break;
			s -= lst;
			lst -= d;
		}
		else{
			if(s-m < 0) break;
			s -= m;
		}

	}
	cout<<i<<"\n";

	return 0;
}