What is the relationship between MasterCard and purchase in the context of the input sentence. Choose an answer from: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

Samuel Ashitey said the MasterCard network in over 220 million shops and businesses in over 210 countries, the SAA Voyager credit card is by far the fastest way to earn miles with a ticket purchase to fly on South Africa Airways or make qualified merchant purchase.

Answer: headquarters_location