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 n=0;
        boolean flag = true;
        while(s>0){
            if(s >= p)    
                n+=1;
            s -= p;
            if(flag){
                p -= d;
                if(p<m){
                    p = m;
                    flag = false; 
                }
            }
        }
        return n;
        // 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();
    }
}