On an `2 x 3` board, there are five tiles labeled from `1` to `5`, and an empty square represented by `0`. A move consists of choosing `0` and a 4-directionally adjacent number and swapping it.

The state of the board is solved if and only if the board is `[[1,2,3],[4,5,0]]`.

Given the puzzle board `board`, return the least number of moves required so that the state of the board is solved. If it is impossible for the state of the board to be solved, return `-1`.

Example 1:

    Input: board = [[1,2,3],[4,0,5]]
    Output: 1
    Explanation: Swap the 0 and the 5 in one move.

Example 2:

    Input: board = [[1,2,3],[5,4,0]]
    Output: -1
    Explanation: No number of moves will make the board solved.

Example 3:

    Input: board = [[4,1,2],[5,0,3]]
    Output: 5
    Explanation: 5 is the smallest number of moves that solves the board.
    An example path:
    After move 0: [[4,1,2],[5,0,3]]
    After move 1: [[4,1,2],[0,5,3]]
    After move 2: [[0,1,2],[4,5,3]]
    After move 3: [[1,0,2],[4,5,3]]
    After move 4: [[1,2,0],[4,5,3]]
    After move 5: [[1,2,3],[4,5,0]]

Constraints:

- `board.length == 2`
- `board[i].length == 3`
- `0 <= board[i][j] <= 5`
- Each value `board[i][j]` is unique.