#include<iostream>
#include<math.h>
#include<string.h>
#include<vector>
#include<algorithm>
#include<iomanip>
#include<deque>
#include<map>
#include<stdio.h>
using namespace std;

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	int a,b,c,d;
	cin >> a >> b >> c >> d;
	int yasai=0;
	int eat=0;
	while(1){
		a--;
		b-=c;
		if(yasai==0 && b<0){
			cout << yasai << endl;
			return 0;
		}
		
		yasai++;
		eat+=(1+c);
		
		if(eat>d||b<0){
			yasai--;
			cout << yasai << endl;
			break;
		}
		
		if(eat==d||a==0||b==0){
			cout << yasai << endl;
			break;
		}
	}
	return 0;
}