What is the relationship between Syriza and ATHENS 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.

ATHENS (Reuters) - Greece's ruling Syriza party edged towards a formal split on Thursday, hours before rebel leftist lawmakers plan to vote against a new bailout deal to keep the country afloat.

Answer: headquarters_location