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

public class Solution {
    
     static int howManyGames(int firstVal, int decreaseVal, int finalVal, int myWallet) {
         int gameNumber = 0;
         int totalAmount = 0;
         
         while(true) {
              if (totalAmount + firstVal <= myWallet) {
                gameNumber++;
                totalAmount += firstVal;
                
                if (firstVal > finalVal) {
                    if (firstVal - decreaseVal < finalVal) {
                        firstVal = finalVal;
                    } else {
                        firstVal -= decreaseVal;   
                    }
                } else {
                    firstVal = finalVal;
                }
            } else {
                break;
            }
         }
         return gameNumber;
     }

    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();
    }
}