Question: Border troops of the country of literature of the country of citizenship of Rainer Ernst are from what country?

Knowledge 1: Literature of East Germany
East German literature is the literature produced in East Germany from the time of the Soviet occupation in 1945 until the end of the communist government in 1990. The literature of this period was heavily influenced by the concepts of socialist realism and controlled by the communist government. As a result, the literature of the German Democratic Republic (East Germany) was for decades dismissed as nothing more than "Boy meet Tractor literature", but its study is now considered a legitimate field. Because of its language, the literature is more accessible to western scholars and is considered to be one of the most reliable, if not the most reliable, sources about East Germany. [SEP] Knowledge 2: Heinz-Josef Große
Heinz-Josef Große was a 34-year-old East German (GDR) construction worker who was shot and killed on 29 March 1982 by GDR border guards on the Inner German border at Schifflersgrund, near Bad Sooden-Allendorf. [SEP] Knowledge 3: Rainer Ernst
Rainer Ernst (born 31 December 1961 in Neustrelitz) is a former German footballer who amassed 56 caps for East Germany.
Knowledge 1: Rainer Ernst
Rainer Ernst (born 31 December 1961 in Neustrelitz) is a former German footballer who amassed 56 caps for East Germany. [SEP] Knowledge 2: Literature of East Germany
East German literature is the literature produced in East Germany from the time of the Soviet occupation in 1945 until the end of the communist government in 1990. The literature of this period was heavily influenced by the concepts of socialist realism and controlled by the communist government. As a result, the literature of the German Democratic Republic (East Germany) was for decades dismissed as nothing more than "Boy meet Tractor literature", but its study is now considered a legitimate field. Because of its language, the literature is more accessible to western scholars and is considered to be one of the most reliable, if not the most reliable, sources about East Germany. [SEP] Knowledge 3: Heinz-Josef Große
Heinz-Josef Große was a 34-year-old East German (GDR) construction worker who was shot and killed on 29 March 1982 by GDR border guards on the Inner German border at Schifflersgrund, near Bad Sooden-Allendorf.
Knowledge 1: Rainer Ernst
Rainer Ernst (born 31 December 1961 in Neustrelitz) is a former German footballer who amassed 56 caps for East Germany. [SEP] Knowledge 2: Literature of East Germany
East German literature is the literature produced in East Germany from the time of the Soviet occupation in 1945 until the end of the communist government in 1990. The literature of this period was heavily influenced by the concepts of socialist realism and controlled by the communist government. As a result, the literature of the German Democratic Republic (East Germany) was for decades dismissed as nothing more than "Boy meet Tractor literature", but its study is now considered a legitimate field. Because of its language, the literature is more accessible to western scholars and is considered to be one of the most reliable, if not the most reliable, sources about East Germany. [SEP] Knowledge 3: Country Sunshine (Dottie West album)
Country Sunshine is an album by Country music singer, Dottie West (released in 1973) based on the successful commercial/Country song of "Country Sunshine".

Answer: GDR