How many athletes were named federico muller?
CREATE TABLE "table1_29521180_35" (
  "athlete" text,
  "event" text,
  "elimination_poule" text,
  "round_of_16" text,
  "quarterfinals" text,
  "semifinals" text,
  "final" text
);
SELECT COUNT("quarterfinals") FROM "table1_29521180_35" WHERE "athlete"='Federico Muller';