Computing grades after tree traversal

   static float grades[][] = new float[100][5];
   static int nstudent = 0;

   private static void compute_final_grades()
   {
      float Ave = 0;
      int i = 0, j = 0;
      System.out.println("Grades");
      for(i = 0; i < nstudent ; i++) 
      {
         float total = 0;
         for(j = 0; j < 4; j++) {
            total += grades[i][j];
         }		
         grades[i][4] = total/4;
         Ave += grades[i][4];
         System.out.println("Student " + i + "=" + grades[i][4]);
      }
      Ave /= nstudent;
      System.out.println("Class Average =" + Ave);  
   }