class A
 def test
  protected_mth
  private_mth
 
  self.protected_mth
  #self.private_mth   #wrong
 
  obj = B.new
  obj.protected_mth
  #obj.private_mth    #wrong
 end
 
 protected
 def protected_mth
  puts "#{self.class}-protected"
 end
 
 private
 def private_mth
  puts "#{self.class}-private"
 end
end
 
class B < A
 def test
  protected_mth
  private_mth
 
  self.protected_mth
  #self.private_mth   #wrong
 
  obj = B.new
  obj.protected_mth
  #obj.private_mth    #wrong
 end
end
 
class C
 def test
  a = A.new
  #a.protected_mth     #wrong
  #a.private_mth      #wrong
 end
end
 
A.new.test
B.new.test
C.new.test