import java.io.*;
import java.util.*;

/**
 *  
 * @author akashvermaofskt
 * Coding is love <3!
 */

class AHack {
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
    static StringTokenizer st = null;
    
    static String next() {
        while (st == null || !st.hasMoreElements()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }
    
    static int nextInt() {
        return Integer.parseInt(next());
    }
    
    static long nextLong() {
        return Long.parseLong(next());
    }

    public static void main(String args[]) {
        try {
            int p=nextInt();
            int d=nextInt();
            int m=nextInt();
            int s=nextInt();
            
            long ans=0;
            long cost=d;
            
            if(p<=s){
                int i;
                for (i = p; i >=m && i<=s; i-=d) {
                    ans++;
                    s-=i;
                    //System.out.println("i "+i);
                }
                
                if(i<m)ans+=s/m;
                
            }
            
            bw.write(ans+"\n");
            bw.flush();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}