import java.util.*;

class Challenge
{
   public static void main(String args[])
   {
       Scanner sc = new Scanner(System.in);
       int p=sc.nextInt();
       int d=sc.nextInt();
       int m=sc.nextInt();
       int s=sc.nextInt();
       int game=0;
       if(s<p)
       {
          System.out.println("0");
          System.exit(0);
       }
       while(0!=1)
       {
           game=1;
           s-=p;
           while(m<=s)
           {
               if(p-d>m)
                 p=p-d;
               else 
                 p=m;
               if(p<=s)
               { s=s-p;
               game++;}
               else break;
               if(p-d<=m)
                p=m;
            }
           System.out.println(game);
           System.exit(0);
       }
    }
}