var n,a,p: integer;
var c: string;
begin
    c:= 'нет';
    read(n);
    p:= -1;
    while n > 0 do
        begin
            a:= n mod 10;
            n:= n div 10;
            if p = a then
                c := 'да';

            p:= a;
        end;
    writeln(c);
end.