2523
On Wednesday  Gerhard Ertl  of  Germany  won the 2007 Nobel Prize in chemistry for studies of chemical reactions on solid surfaces which are key to understanding such questions as why the ozone layer is thinning .
 countries of residence: Gerhard Ertl, Germany
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:
 countries of residence: Gerhard Ertl, Germany