What is the name of the Count Palatine of the Rhine with a Interregnum began of 2 april 1657 death of ferdinand iii?
CREATE TABLE "list_of_imperial_vicars_1437_1792" (
  "interregnum_began" text,
  "interregnum_ended" text,
  "duration" text,
  "count_palatine_of_saxony" text,
  "count_palatine_of_the_rhine" text
);
SELECT "count_palatine_of_the_rhine" FROM "list_of_imperial_vicars_1437_1792" WHERE "interregnum_began"='2 april 1657 death of ferdinand iii';