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

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

begin
  index := -1;

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

  for i := 1 to n do
  begin
    if (abs(arr[i]) mod 2) = 1 then index := i;
  end;
  if index = -1 then
    writeln('NO')
  else
   writeln(index);
end.