5450
He returned to Germany in November 1918 upon an invitation from Fritz Kater to join him in Berlin to re-build the  Free Association of German Trade Unions  (  FVdG  ) .
 alternate names: Free Association of German Trade Unions, FVdG
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:
 alternate names: Free Association of German Trade Unions, FVdG