Question:  Dulwich College is a member of an association of how many independent schools?

Context paragraphs:
New Jersey Association of Independent Schools: The New Jersey Association of Independent Schools (NJAIS) serves independent elementary and secondary schools throughout the state of New Jersey.  The Association consists of 70 member schools with a total enrollment of approximately 26,000 students.  The New Jersey Association of Independent Schools is the representative organization of independent schools throughout the state of New Jersey.  It promotes and supports educational, ethical, and professional excellence in member schools, and works to protect their independence through advocacy at the local, state, and federal levels.

The Galloway School: The Galloway School is a private, co-educational day school in Atlanta, Georgia, United States.  It was founded by Elliott Galloway in 1969 designed to offer an academic program for children ages 3 through grade 12.  The school has been accredited by is a member of the National Association of Independent Schools (NAIS), the Southern Association of Independent Schools (SAIS), the Georgia Independent School Association (GISA), the Atlanta Area Association of Independent Schools (AAAIS) and the National Association for College Admission Counseling (NACAC).

First Assembly Christian School: First Assembly Christian school (FACS) is a college preparatory school located in the Cordova section of Memphis, Tennessee.  FACS was founded in 1972; programs for kindergarten through Grade 8 began in 1972 and grades 9-12 were added in 1975.  The school is fully accredited by the Southern Association of Colleges and Schools.  First Assembly is also a member of the Association of Christian Schools International, Southern Association of Independent Schools, Tennessee Association of Independent Schools, Memphis Association of Independent Schools, and the College Board.  Though strongly supported by First Assembly of God Church, of the Assemblies of God, the school's website identifies itself as Non-denominational Christian.

Independent Schools Inspectorate: The Independent Schools Inspectorate (ISI) is an organisation responsible for the inspection of independent schools in England which are members of organisations affiliated to the Independent Schools Council (ISC).  It is one of three independent schools inspectorates empowered to carry out inspections through an agreement with the Department for Education (DfE).  As of January 2012, ISI also inspects all boarding school welfare provision for the schools within its remit, making it the largest inspectorate of school boarding provision in the UK.  ISI's work is monitored by Ofsted on behalf of the DfE.  Independent schools which are not members of the ISC are mostly inspected by Ofsted but some are inspected by the Schools Inspection Service (SIS) or Bridge Schools Inspectorate (BSI).  ISI is a DfE approved inspectorate for British Schools Overseas and provides education services, including inspection, in all the continents of the world except Antarctica and Australia.

Independent Schools' Bursars Association: The Independent Schools’ Bursars Association originated as the Public Schools Bursars' Association.  The first general meeting was held on 26 April 1932 at Epsom College.  The organization changed its name to "the Independent Schools' Bursars Association" in 1983.  The Association is a registered charity; its stated object is "the advancement of education by the promotion of efficient and effective administration and ancillary services at independent schools."  The Association provides support for bursars in independent schools and promotes good practices.  Individual schools are members of the association; most schools select their bursar as the representative to the Association.

Headmasters' and Headmistresses' Conference: The Headmasters' and Headmistresses' Conference (HMC) is an association of the headmasters or headmistresses of 283 independent schools (both boarding schools and day schools) in the United Kingdom, Crown dependencies and the Republic of Ireland.  For 2016/2017 the average day fees at a UK HMC school are £4,639 per term or £13,917 per annum.  For 2016/2017 the average full boarding fees at a UK HMC school are £10,709 per term or £32,127 per annum.

Dulwich College: Dulwich College is a boarding and day independent school for boys in Dulwich in southeast London, England.  It was founded in 1619 by Edward Alleyn, an Elizabethan actor, with the original purpose of educating 12 poor scholars as the foundation of "God's Gift".  It currently has about 1,500 boys, of whom 120 are boarders.  Admission by examination is mainly into years 3, 7, 9, and 12 (i.e. ages 7, 11, 13, and 16 years old) to the Junior, Lower, Middle and Upper Schools into which the college is divided.  It is a member of both the Headmasters' and Headmistresses' Conference and the Eton Group.

Dulwich College Beijing: Dulwich College Beijing (Simplified Chinese: 北京德威英国国际学校, Traditional Chinese: 北京德威英國國際學校, Pinyin: "Běijīng Déwēi Yīngguó Guójì Xuéxiào" "Beijing Dulwich English International School") is a British international school with campuses in Beijing, China.  It is a branch of Dulwich College, and opened in August 2005.  As of 2013 it has over 1,450 students from 12 months to 18 years.

New York State Association of Independent Schools: The New York State Association of Independent Schools (NYSAIS) is an association of 194 independent schools, ranging from nurseries to high schools, in New York State.  Founded in 1947, NYSAIS is the second largest state association of independent schools in the United States.  In 2017 its member schools enrolled approximately 82,000 students.  It was established ""to protect independent schools from obstructive legislation and regulation"".  NYSAIS accredits its member schools, provides professional development, and works with community leaders to support the needs and interests of independent schools throughout the state.  NYSAIS is a member of the National Association of Independent Schools (NAIS) as well the NAIS Commission on Accredition.

Virginia Association of Independent Schools: Virginia Association of Independent Schools (VAIS) is a non-profit, voluntary membership association of schools within the state of Virginia.  The VAIS is a member of the National Association of Independent Schools.  Prior to its establishment in Charlottesville, Virginia on April 30, 1973, a small number of independent schools’ headmasters known as “The Baker’s Dozen” met informally, teachers at their independent schools held conferences, and development coordinators hosted their own meetings to discuss commonly held educational issues.  While the Virginia State Department of Education accredits independent and other nonpublic pre-school, elementary and secondary schools via the Virginia Council for Private Education (VCPE), the VAIS is a service organization that promotes educational, ethical and professional excellence.

Supporting paragraphs: Dulwich College Headmasters' and Headmistresses' Conference
Answer: 283