10468
Keith B. Alexander ( born December 2 1951 ) is the current Director  National Security Agency  ( DIRNSA ) Chief Central Security Service ( CHCSS ) and Commander  United States  Cyber Command .
 country of headquarters: National Security Agency, United States
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:
 country of headquarters: National Security Agency, United States