#include <iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<map>
#include<cstdio>
using namespace std;

int main(){
	int a, b, c, d;
	cin >> a >> b >> c >> d;
	if (a*c <= b) {
		if (a*c + a <= d) {
			cout << a << endl;
		}
		else {
			d = d - d % (c + 1);
			cout << d / (c + 1)<<endl;
		}
	}
	else {
		int f = (b - b % c) / c + b - b % c;
		if (f<=d){ 
			b = b - b % c;
			cout << b/c << endl;
			}
		else {
			d = d - d % (c + 1);
			cout << d / (c + 1) << endl;
		
		}
	}
	return 0;
}