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
        int NrGame = 0;
        for(int i = 0;s-p >= 0;i++){
            
            
            s = s - p;
            NrGame++;
            if( p - d <= m){
                p = m;
                continue;
            }else{
            p = p - d;
            
            }
            
            }
        return NrGame;
        }
        
           
    

    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();
    }
}