Im a newb still studying java programming
wats wrong with my scripts help..?

 public class Sample1
  {
      public static void main (String[] args)
     {
       String desc;
        if (mark >= 85)
           desc = "Very Good";
        else
           if (mark >= 70)
              desc= "Good";
           else
              if (mark >= 50)
                 desc= "Adequate";
              else
                 desc = "Poor";

        System.out.println ("Description=" +desc);
     }
  }

The error ->
Sample1.java:6: cannot find symbol
symbol  : variable Mark
location: class Sample1
        if (Mark >= 85)
                    ^
Sample1.java:9: cannot find symbol
symbol  : variable Mark
location: class Sample1
           if (Mark >= 70)
               ^
Sample1.java:12: cannot find symbol
symbol  : variable Mark
location: class Sample1
              if (Mark >= 50)
                  ^
3 errors

btw im using JGrasp software..=) help pls...