Set

uses
  SysUtils, StrUtils;
 
const
  pr=124991;
type
  List=^u;
    u=record
      key:Integer;
      next:List;
    end;
var
  f,g:Text;
  s,s1:string;
  x,r:Integer;
  a:array[0..pr] of List;
 
procedure inserthash(x:Integer);
  var
    n:Integer;
    q,p:List;
  begin
    r:=0;
    n:=Abs(x) mod pr;
    if a[n]=nil then
      begin
        New(q);
        q^.key:=x;
        q^.next:=nil;
        a[n]:=q;
      end
    else
      begin
        q:=a[n];
        while (q^.key<>x) and (q^.next<>nil) do
          q:=q^.next;
        if (q^.next=nil) and (q^.key<>x) then
          begin
            New(p);
            p^.key:=x;
            p^.next:=nil;
            q^.next:=p;
          end;
      end;
  end;
 
procedure DeleteHash(x:Integer);
  var
    n:Integer;
    q,p:List;
  begin
    r:=2;
    n:=Abs(x) mod pr;
    if a[n]<>nil then
      begin
        q:=a[n];
        p:=nil;
        while (q^.key<>x) and (q^.next<>nil) do
          begin
            p:=q;
            q:=q^.next;
          end;
        if (q^.key=x) then
          begin
            if p=nil then
              a[n]:=a[n]^.next
            else
              begin
                p^.next:=q^.next;
                Dispose(q);
              end;
          end;
      end;
  end;
 
procedure ExistsHash(x:Integer);
  var
    n:Integer;
    q:List;
    y:Boolean;
  begin
    r:=4;
    y:=False;
    n:=Abs(x) mod pr;
    if a[n]<>nil then
      begin
        q:=a[n];
        while (q^.key<>x) and (q^.next<>nil) do
          begin
            q:=q^.next;
          end;
        if (q^.key=x) then
          begin
            y:=True;
          end;
      end;
    if y=True then
      Writeln(g,'true')
    else
      Writeln(g,'false');
  end;
 
begin
  Assign(f,'set.in');
  Assign(g,'set.out');
  reset(f);
  rewrite(g);
  while not Eof(f) do
    begin
      Readln(f,s);
      s1:=s[1];
      delete(s,1,Pos(' ',s));
      x:=StrToInt(s);
      if s1='i' then
        begin
          inserthash(x);
        end;
      if s1='d' then
        begin
          DeleteHash(x);
        end;
      if s1='e' then
        begin
          ExistsHash(x);
        end;
    end;
  close(F);
  Close(G);
end.