This task involves creating answers to complex questions, from a given passage. Answering these questions, typically involve understanding multiple sentences. Make sure that your answer has the same type as the "answer type" mentioned in input. The provided "answer type" can be of any of the following types: "span", "date", "number". A "span" answer is a continuous phrase taken directly from the passage or question. You can directly copy-paste the text from the passage or the question for span type answers. If you find multiple spans, please add them all as a comma separated list. Please restrict each span to five words. A "number" type answer can include a digit specifying an actual value. For "date" type answers, use DD MM YYYY format e.g. 11 Jan 1992. If full date is not available in the passage you can write partial date such as 1992 or Jan 1992. If you find multiple spans, please add them all as a comma separated list. Please restrict each span to five words.

Passage: While working for his PhD, he collaborated concurrently with the Swiss urban planner Professor Arnold Hoechel and the architects Frei and Hunziker on several projects, including the first automatic bowling alleys in Meyrin Commune, Geneva, and Beirut, Lebanon. In 1961, he returned to Tehran as Deputy Technical Director of Iran-Rah, the largest Construction Co. of its time in Iran. In 1963, he created his own firm under the name of Borbor Consulting Architects, Engineers, City Planners. As President and managing director, he developed and expanded the business to a large multidisciplinary organization with several in-house departments which included: architecture, urban planning, environment, structure, mechanics, electricity and interior design. The firm employed a large number of highly qualified multi-national staff and included branch offices in several major cities in Iran. A few months prior to the 1978 Iranian Islamic Revolution, Borbor moved to Paris, France where he founded the Borbor International Management Consultants to Architects, Engineers, Planners. BIMC offered consultancy services in design, management and documentation to architectural and planning firms. In 1984, he moved to Los Angeles where he was involved in some architectural consultancy and research on Iranian and Persianate subjects. Borbor returned to Iran in 1991 and established the Research Institute and Library of Iranian Studies , a non-profit, non-political, private and independent institution dedicated to the promotion of research in the field of Iranian and Persianate studies with special emphasis on novel and creative research.
Question: How many architects did Arnold Hoechel work with?
Answer type: Number
2.