UVA Problem ID 573 ( The Snail )

import java.io.*;
import java.util.StringTokenizer;

public class Main {

     static String ReadLn (int maxLg)  // utility function to read from stdin
     {
         byte lin[] = new byte [maxLg];
         int lg = 0, car = -1;
         String line = "";

         try
         {
             while (lg < maxLg)
             {
                 car = System.in.read();
                 if ((car < 0) || (car == '\n')) break;
                 lin [lg++] += car;
             }
         }
         catch (IOException e)
         {
             return (null);
         }

         if ((car < 0) && (lg == 0)) return (null);  // eof
         return (new String (lin, 0, lg));
     }

     public static void main (String args[])  // entry point from OS
     {
         Main myWork = new Main();  // create a dynamic instance
         myWork.Begin();            // the true entry point
     }

     void Begin()
     {
         String input;
         StringTokenizer st;
         while ((input = Main.ReadLn (255)) != null)
         {
          st=new StringTokenizer(input);
          int H=Integer.parseInt(st.nextToken());
          int U=Integer.parseInt(st.nextToken());
          int D=Integer.parseInt(st.nextToken());
          int F=Integer.parseInt(st.nextToken());
          if(H==0)
          {
           System.exit(0);
          }
          float previousheight=0;
          int days=1;
          while(true)
          {
           float climbingdistance=(U-((days-1)*U*(float)F/100));
           float y=previousheight;
           if(climbingdistance > 0)
           {
            y=previousheight+climbingdistance;
            //System.out.println("y ="+y+" previousheight "+previousheight);
           }
           if(y>H)
           {
            System.out.println("success on day "+days);
            break;
           }
           if(y<=H && y>=0)
           {
            y=y-D;
           }
           if(y<0)
           {
            System.out.println("failure on day "+days);
            break;
           }
           days++;
           previousheight=y;
           
          }
         }
     }
}