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 remainingMoney = s;
        int currentValue = p;
        int count = 0;
        while(true){
            if(currentValue <= remainingMoney){
                count++;
                remainingMoney -= currentValue;
                if(currentValue > m){
                    currentValue -= d;
                    if(currentValue < m )
                        currentValue = m;
                }
                
            }
            else
                break;
        }
        return count;
    }

    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();
    }
}