Who was the young rider classification when Diego Ulissi won? 
CREATE TABLE "classification_leadership" (
  "stage" real,
  "winner" text,
  "general_classification" text,
  "points_classification" text,
  "mountains_classification" text,
  "young_rider_classification" text
);
SELECT COUNT("young_rider_classification") FROM "classification_leadership" WHERE "winner"='Diego Ulissi';