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 numOfGames = 0;
        int currentSum = 0;
        
        currentSum += p;
        if (currentSum <= s) {
            //System.out.println(p + ", " + numOfGames + ", " + currentSum);
            numOfGames++;
        }
        while(p > m) {
            p -= d;
            if (p < m)
                break;
            currentSum += p;
            //System.out.println(p + ", " + numOfGames + ", " + currentSum);
            if (currentSum <= s) {
                numOfGames++;
            } else {
                return numOfGames;
            }
        }
            
        while (currentSum <= s) {
            //System.out.println(m + ", " + numOfGames + ", " + currentSum);
            currentSum += m;
            numOfGames++;
        }
        numOfGames--;
        return numOfGames;
    }

    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();
    }
}