program Project3;

{$APPTYPE CONSOLE}

uses
  SysUtils,
  Math;

const
  max_n = 100000;

type
  Tree = ^Node;
  Node = record
    l_son, r_son, parent: Tree;
    key, value: longint;
  end;

var
  s, num: string;
  x, i, counter, cur: longint;
  build: Tree;
  flag: boolean;
  ch1, ch2: char;
  arr: array [1..max_n] of longint;

function search_key(tree_key: longint): boolean;
var
  t: longint;
begin
  search_key := false;

  for t := 1 to counter do
    if (arr[t] = tree_key) then
      search_key := true;
end;

procedure QSort(lt, rt: longint);
var
  i, j, x_key, tmp: longint;
begin
  i := lt;
  j := rt;
  x_key := arr[(lt + rt) div 2];

  repeat
    while (arr[i] < x_key) do
      inc(i);
    while (arr[j] > x_key) do
      dec(j);
    if (i <= j) then begin
      tmp := arr[i];
      arr[i] := arr[j];
      arr[j] := tmp;
      inc(i);
      dec(j);
    end;
  until i > j;

  if (lt < j) then
    QSort(lt, j);
  if (i < rt) then
    QSort(i, rt);
end;

procedure delete(tree_key: longint);
var
  t: longint;
begin
  for t := 1 to counter do
    if (arr[t] = tree_key) then begin
      arr[t] := arr[counter];
      counter := counter - 1;
      exit;
    end;

  QSort(1, counter);
end;

function next_search(tree_key: longint): longint;
var
  t: longint;
begin
  QSort(1, counter);

  for t := 1 to counter do
    if (arr[t] > tree_key) then begin
      next_search := arr[t];
      exit;
    end;

  flag := false;
end;

function prev_search(tree_key: longint): longint;
var
  t: longint;
begin
  QSort(1, counter);

  for t := counter downto 1 do
    if (arr[t] < tree_key) then begin
      prev_search := arr[t];
      exit;
    end;

  flag := false;
end;

procedure insert(tree_key: longint);
begin
  counter := counter + 1;
  arr[counter] := tree_key;

  QSort(1, counter);
end;

begin
  reset(input, 'bstsimple.in');
  rewrite(output, 'bstsimple.out');

  New(build);
  build := nil;
  counter := 0;

  randomize;
  randseed := 17000;

  while not eof do begin
    num := '';
    read(ch1);
    read(ch2);
    while(ch2 <> ' ') do
      read(ch2);
    readln(x);

    if (ch1 = 'i') then
      if (search_key(x) = false) then
        insert(x);

    if (ch1 = 'd') then
      if (search_key(x) <> false) then
        delete(x);

    if (ch1 = 'e') then begin
      if (search_key(x) = true ) then
        writeln('true')
      else
        writeln('flase');
    end;

    if (ch1 = 'n') then
    begin
      flag := true;
      cur := next_search(x);

      if (flag) then
        writeln(cur)
      else
        writeln('none');
    end;

    if (ch1 = 'p') then begin
      flag := true;
      cur := prev_search(x);

      if (flag) then
        writeln(cur)
      else
        writeln('none');
    end;
  end;

  closefile(output);
end.