11443
On September 1 2010 he entered the  Discovery Communications  headquarters building in  Silver Spring  Maryland with a gun and several bombs strapped to his body and took three hostages .
 city of headquarters: Discovery Communications, Silver Spring
Given a phrase that describes the relationship between two words, extract the words and the lexical relationship between them. The output format should be "relation1: word1, word2; relation2: word3, word4". 
Option: cities of residence, top members employees, members, alternate names, origin, state or provinces of residence, title of person, spouse, city of headquarters, NA, founded by, state or province of headquarters, employee of, countries of residence, country of birth, founded, subsidiaries, country of headquarters 
Text: {0} 
Answer:
 city of headquarters: Discovery Communications, Silver Spring