Input (grade 13): Poland regained its independence as the Second Polish Republic in 1918, after World War I, but was later occupied by Nazi Germany and the Soviet Union during World War II.
Output (grade 8): Poland regained its independence in 1918 after World War I but lost it again in World War II. On September 1, 1939, World War II started when Nazi Germany attacked Poland, and the Soviet Union attacked on September 17.