private int findNeededCallsForNextLevel(int[][] board) {
        int r = 0;
        for (Move move : Move.ALL) {
            int[][] newBoard = makeMove(board, move);
            if (OriginalGamePlayer.equals(board, newBoard)) {
                continue;
            }
            for (int i = 0; i < board.length; i++) {
                for (int j = 0; j < board[i].length; j++) {
                    if (newBoard[i][j] == 0) {
                        r += 2;  // can put 2 or 4
                    }
                }
            }
        }
        return r;
    }