#include <bits/stdc++.h>
using namespace std;

int main() {
	int p, d, m, s, ctr = 0;
	cin >> p >> d >> m >> s;
	while(s > 0) {
 		if(s < p) break;
		s -= p;
		ctr++;
		if(p > m) {
			if(p - d > m) p -= d;
			else p = m;
		}
	}
	
	cout << ctr;
	return 0;
}