Who was awarded mountains classifications when Mikel Nieve was the winner? 
CREATE TABLE "classification_leadership" (
  "stage" real,
  "winner" text,
  "general_classification" text,
  "points_classification" text,
  "mountains_classification" text,
  "combination_classification" text,
  "team_classification" text
);
SELECT "mountains_classification" FROM "classification_leadership" WHERE "winner"='Mikel Nieve';