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) {
        // Return the number of games you can buy
        if(p>s) return 0;
        else if(p==s)return 1;
        boolean flag = true;
        int cnt = 1;
        int prev = p;
        s-=p;
        while(true){
            
            if((prev - d)>m){
                prev -= d;
            }else{
                prev = m;
            }
            s-=prev;
            if(s<0)break;
            cnt++;
        }
        return cnt;
    }

    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();
    }
}