{$IFDEF NORMAL}
  {$I-,Q-,R-,S-}
{$ENDIF NORMAL}
{$IFDEF DEBUG}
  {$I+,Q+,R+,S-}
{$ENDIF DEBUG}
{$IFDEF RELEASE}
  {$I-,Q-,R-,S-}
{$ENDIF RELEASE}

var fi,fo:text;
    e,i,j,n,vl,ant,maxc,lung,max,cr:integer;
    ok,found,ind:boolean;
    a:array[1..2002] of integer;
    p:array[1..2002] of integer;
    sol:array[1..1000] of integer;
    s:string[1];

begin
assign(fi,'elimin2.in'); reset(fi);
assign(fo,'elimin2.out'); rewrite(fo);
i:=1;
while not( eoln(fi)) do
 begin

  read(fi,s);
  val(s,a[i],e);
  inc(i);
 end;
n:=i-1;
ok:=true;
for i:=1 to n div 2 do
  if a[i]<>a[n-i+1] then ok:=false;
if ok then
 begin
  for i:=1 to n do
   write(fo,a[i]);
   close(fo);
   halt;
 end;
end.