Program Palindrom;
uses crt;
type mas=array[1..10] of integer;
var  n,n0,kil,ch,ch1,kil1,i,k,hh,q,kk,s:integer;
f,g:text;     p:mas;
procedure prog(p:mas; n:integer;var ch,kil,kk:integer;pp:mas );
begin
pp[i]:=p[i];
  ch:=1;
  kil:=5;
  i:=1;


k:=0;
for i:=1 to n do
begin k:=k+1;
if (p[i]+1)=(p[i+1]) then
 begin
s:=i;
 hh:=0;
end;end;


q:=1;
q:=q+1;

kk:=(k-q);

if hh=0 then begin

  kil:=0;
  for i:=1 to kk do
 begin
 kil:=kil+1;
 end;    end;
end;
procedure Vvod(var ch,kil:integer);
 var p:mas;
 begin
assign(f,'palidrom.dat');
reset(f);
read(f,n); readln(f);
for i:=1 to n do
begin
read(f,p[i]);
end;
prog(p,n,ch,kk,kil,p);
end;

procedure vuvid(ch,kil,kk:integer;pp:mas);
begin
assign(g,'palidrom.sol');
rewrite(g);
write(g,kil); writeln(g);
for i:=1 to kk do
begin
write(g,p[i]);
 end;

end;
Begin clrscr;
vvod(ch,kil);

vuvid(ch,kil,kk,p);
close(f);
close(g);
end.