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

var
  arr : arrayType;
  i : integer;
  index : integer;
  flag : boolean;

begin
  index := -1;
  flag := False;

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

  for i := 1 to n do
  begin
    if ((abs(arr[i]) mod 2) = 0) and (not flag) then
    begin
      if not (index = -1) then flag := True;
      index := i;
    end;
  end;
  if not flag then
    writeln('NO')
  else
   writeln(index);
end.