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 sum=p;
        int c=0;
        int count=1;
        p-=d;
        while(sum <= s){
        //    System.out.print(p+" ");
            if((p) < m){
                sum+=m;
            }
            else{
                sum+=(p);
                p-=d;
            }
            count++;
             //System.out.println(p+" ");
        }
        // Return the number of games you can buy
        return count-1;
    }

    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();
    }
}