With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Norovirus is also known as the winter vomiting bug.
text_B: Central London is the innermost part of London , UK .. There is no official definition of its area but its characteristics are understood to include a high density built environment , high land values , an elevated daytime population and a concentration of regionally , nationally and internationally significant organisations and facilities .. Over time a number of definitions have been used to define the scope of central London for statistics , urban planning and local government .. Road distances to London are traditionally measured from a central point at Charing Cross -LRB- in the City of Westminster -RRB- , which is marked by the statue of King Charles I at the junction of the Strand , Whitehall and Cockspur Street , just south of Trafalgar Square .. Charing Cross. Charing Cross. City of Westminster. City of Westminster. statue of King Charles I. Statue of King Charles I, London. Strand. Strand, London. Whitehall. Whitehall. Cockspur Street. Cockspur Street. Trafalgar Square. Trafalgar Square
not_related.