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

public class Solution {

    static int howManyGames(int p, int d, int m, int s) {
            
            int gameCount=0;
            int prev=p;
            while (s>0 && s>=p){
                    if (s<m)
                            break;
                    if (p>m){
                      s-=p;
                      gameCount++;
                      p-=d;      
                    }else{
                        s-=m;
                      gameCount++;
                      p=m;  
                    }  
            }
            
            return gameCount;
        // Return the number of games you can buy
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int p = in.nextInt();
        int d = in.nextInt();
        int m = in.nextInt();
        int s = in.nextInt();
        int answer = howManyGames(p, d, m, s);
        System.out.println(answer);
        in.close();
    }
}