Question: How many children does this novel by Stephen King center around that along with "Insomnia" and "Dreamcatcher" takes place in a fictional town Derry, Maine?

Context paragraphs:
Crimson King: The Crimson King, known to some as Los' or Ram Abbalah, is a fictional character created by Stephen King.  He is the primary antagonist of King's eight-volume "Dark Tower" series, as well as the novels "Insomnia" and "Black House".  Described as "Gan's crazy side", the Crimson King is the ultimate ruler of the Red (also called the Random and the Outer Dark), and the archetypal embodiment of evil in Stephen King's fictional multiverse.  His goal is to topple the Dark Tower which serves as the linchpin of time and space, destroying the multitude of universes which revolve around it so that he can rule in the primordial chaos which follows.

East Derry, New Hampshire: East Derry, also known as the Upper Village, is an unincorporated community in the town of Derry in Rockingham County, New Hampshire.  The village center constitutes the East Derry Historic District, listed on the National Register of Historic Places.  It is located on a hill close to the geographic center of the town of Derry along East Derry Road, approximately 2 mi east of the built-up town center of Derry.  East Derry has a separate ZIP code (03041) from the rest of the town of Derry.  Alan Shepard lived in the village as a boy.  Station #4 of the Derry Fire Department is located in the village.

Maiden City Festival: The Maiden City Festival (Ulster-Scots: tha "Maiden Citie Blythe-Tid") takes place in Derry, Northern Ireland in the second week in August each year.  In 2008 the Festival was described as a "diverse, varied programme of events that underscores the organisers' desire to provide something for everyone", as well as a "showcase for Protestant tolerance and openness".  Events included Bluegrass on the Walls, Children's Heritage Visual Art Workshops, drumming events, including some with members of the north west's African community, music of all kinds at the Verbal Arts Centre, Foyle Ulster Scots Highland Gathering, firwework display, the fifth Annual Scottish Dance Competition, historical walks and talks, with the finale being the Relief of Derry Pageant (the Apprentice Boys of Derry 319th Relief of Derry Celebrations) on 9 August 2008.  The Festival commemorates the actions of Protestant Apprentice Boys who shut the city gates against the forces of the Catholic King James in December 1688.  King James laid siege to the city from December to August 1689 until the Protestant forces of William of Orange relieved the city.

It (novel): It is a 1986 horror novel by American author Stephen King.  It was his 22nd book and 18th novel written under his own name.  The story follows the experiences of seven children as they are terrorized by a being that exploits the fears and phobias of its victims to disguise itself while hunting its prey.  "It" primarily appears in the form of a clown to attract its preferred prey of young children.

Derry (Stephen King): Derry is a fictional town and a part of Stephen King's fictional Maine topography.  Derry has served as the setting for a number of his novels, novellas, and short stories.  Derry first appeared in King's 1981 short story "The Bird and the Album" and has reappeared as late as his 2011 novel "11/22/63" (see list below).  Derry is said to be near Bangor, but King has acknowledged that Derry is actually his portrayal of Bangor.  A map on King's official website, though, places Derry in the vicinity of the town of Etna.

Jerusalem's Lot (Stephen King): Jerusalem's Lot, Maine (often shortened to 'Salem's Lot or just the Lot) is a fictional town and a part of writer Stephen King's fictional Maine topography.  'Salem's Lot has served as the setting for a number of his novels, novellas, and short stories.  'Salem's Lot first appeared in King's 1975 novel "'Salem's Lot", and has reappeared as late as his 2013 novel "Doctor Sleep" (see list below).  The town is described as being located in Cumberland County, between (or including parts of) the towns of Falmouth, Windham, and Cumberland, near the southern part of the state about ten miles north of Portland.  A map on King's official website, though, places 'Salem's Lot considerably further north, approximately in Northwest Piscataquis.

Rose Madder (novel): Rose Madder is a fantasy novel by American writer Stephen King, published in 1995.  It deals with the effects of domestic violence (which King had touched upon before in the novels "It", "Insomnia", "Dolores Claiborne", "Needful Things", and many others) and, unusually for a King novel, relies for its fantastic element on Greek mythology.  In his memoir, "", King states that "Rose Madder" and "Insomnia" are "stiff, trying-too-hard novels."

Carrie (novel): Carrie is a novel by American author Stephen King.  It was his first published novel, released on April 5, 1974, with an approximate first print-run of 30,000 copies.  Set primarily in the then-future year of 1979, it revolves around the eponymous Carrie White, a misfit and bullied high school girl who uses her newly discovered telekinetic powers to exact revenge on those who torment her, while in the process causing one of the worst local disasters in American history.  King has commented that he finds the work to be "raw" and "with a surprising power to hurt and horrify."  It is one of the most frequently banned books in United States schools.  Much of the book uses newspaper clippings, magazine articles, letters, and excerpts from books to tell how Carrie destroyed the fictional town of Chamberlain, Maine while exacting revenge on her sadistic classmates and her own mother Margaret.

Insomnia (novel): Insomnia is a horror/fantasy novel by American writer Stephen King, first published in 1994.  Like "It" and "Dreamcatcher", its setting is the fictional town of Derry, Maine.  The original hardcover edition was issued with dust jackets in two complementary designs.  The first is pictured on the right; the second has the white and red colors reversed.  In his memoir, "", King states that "Insomnia" and "Rose Madder" are "stiff, trying-too-hard novels.”

Unpublished and uncollected works by Stephen King: According to books by Tyson Blue ("The Unseen King"), Stephen J. Spignesi ("The Lost Work of Stephen King"), and Rocky Wood "et al." ("Stephen King: Uncollected, Unpublished"), there are numerous unpublished works by Stephen King that have come to light throughout King's career.  These allegedly include novels and short stories, most of which remain unfinished.  Most are stored among Stephen King's papers in the special collections of the Raymond H. Fogler Library at the University of Maine, some of which are freely accessible to the library's visitors.  However, others require King's permission to read.  Additionally, there are a number of uncollected short stories, published throughout King's long career in various anthologies and periodicals, that have never been published in a King collection.

Supporting paragraphs: Insomnia (novel) It (novel)
Answer: seven