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

public class Solution {
    void run() throws Exception{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String [] xyz = br.readLine().trim().split(" ");
        int p = Integer.parseInt(xyz[0]);
        int d = Integer.parseInt(xyz[1]);
        int m = Integer.parseInt(xyz[2]);
        int s = Integer.parseInt(xyz[3]);
        
        int price = 0;
        int count = 0;
        while(s > 0){
            if(p > s){
                break;
            }else{
                if(p <= m){
                    d = 0;
                    p = m;
                }
                s = s-p;
                p = p - d;
                if(s >= 0)
                    count++;
            }
        }
        System.out.println(count);
    }
    public static void main(String[] args) throws Exception {
        Solution obj = new Solution();
        obj.run();
    }
}