procedure insert(in/out:root;in elem)
begin
      var albero: root,new_node
      var integer: elem
      if(empty(root))then
         new_node.info:=elem
         new_node.left:=NULL
         new_node.right:=NULL
         root=new_node
      else
         if(elem<root.info)then
            insert(root.left,elem)
         else
            if(elem>root.right)then
               insert(root.right,elem)
            else
               print("Elemento già inserito")
            endif
          endif
        endif
end insert