CREATE TABLE table_53876 ("Interregnum began" TEXT, "Interregnum ended" TEXT, "Duration" TEXT, "Count Palatine of Saxony" TEXT, "Count Palatine of the Rhine" TEXT)

What is the Interregnum ended for Count Palatine of Saxony of frederick augustus i, elector of saxony?
SELECT "Interregnum ended" FROM table_53876 WHERE "Count Palatine of Saxony" = 'frederick augustus i, elector of saxony'
SELECT "Interregnum ended" FROM "table_53876" WHERE "Count Palatine of Saxony" = 'frederick augustus i, elector of saxony'