CREATE TABLE table_17564 ("Stage" TEXT, "Winner" TEXT, "General classification" TEXT, "Points classification" TEXT, "Mountains classification" TEXT, "Young rider classification" TEXT, "Intergiro classification" TEXT, "Trofeo Fast Team" TEXT)

Who's the winner in stage 1a, where the leader in the young rider classification is Francesco Casagrande?
SELECT "Winner" FROM table_17564 WHERE "Young rider classification" = 'Francesco Casagrande' AND "Stage" = '1a'
SELECT "Winner" FROM "table_17564" WHERE "Stage" = '1a' AND "Young rider classification" = 'Francesco Casagrande'