let mov_pos b =
    match b with
    [] -> []
    | (h::t) ->
        let board_size = find_board_size(b) in
        let pos = index(b, 0) in
        let real_pos = pos mod board_size in
        let narr = if real_pos > 0 then get_val(b, pos-1)::narr else narr in
        let narr =  if real_pos < board_size-1 then get_val(b, pos+1)::narr else narr in
        let narr =  if pos > board_size-1 then get_val(b, pos-board_size)::narr else narr in
        if pos < board_size*2 then get_val(b, pos+board_size)::narr else narr
;;