#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fr(i,a,b) for(ll i=a;i <= b;i++)
#define fast_io ios_base::sync_with_stdio(false)
#define fd(i,a,b) for(ll i=a;i >= b;i--)
#define rep(i,n) for(ll i=0;i < n;i++)
#define sz(x) x.size()
#define N 100005

int main() {
	fast_io;
	ll p,d,m,s,cnt = 0; cin >> p >> d >> m >> s;
	ll pre = p;
	bool res = false;
	while(s >= 0) {
		s -= pre;
		if(s >= 0) cnt++;
		if(res) pre = m;
		else {
			if(pre - d > m) {
				pre -= d;
			}
			else {
				pre = m;
				res = true;
			}
		}
	}
	cout << cnt << endl;
}