import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
   static BufferedReader bf=new BufferedReader(new InputStreamReader(System.in));
   static int p;
   static int m;
   static int s;
   static int count;
    public static void main(String[] args)throws Exception {
        String ss=bf.readLine();
        StringTokenizer stk=new StringTokenizer(ss);
         p=Integer.parseInt(stk.nextToken());
        int d=Integer.parseInt(stk.nextToken());
         m=Integer.parseInt(stk.nextToken());
          s=Integer.parseInt(stk.nextToken());
          while(s>=m && s>=p){
            count++;
            if(p>m){
              s=s-p;
              p=p-d;
            }else{
              s=s-m;
            }
          }
          System.out.println(count);
    }
}