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 v=p; int c=0; while(v<=s) {int x=p-d; p=x; if(x>m) { v+=x; c++;} else { v+=m;c++;} } return c; } 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(); } }