type
  arrayType = array[1..n] of integer;

var
  arr : arrayType;
  i : integer;
  val : integer;

begin
  val := 0;

  for i := 1 to n do readln(arr[i]);

  for i := 1 to n do
  begin
    if (arr[i] < 0) and (val = 0) then val := arr[i];
  end;
  if val = 0 then
    writeln('NO')
  else
   writeln(val);
end.