CREATE TABLE activity (actid DECIMAL, activity_name TEXT)
CREATE TABLE faculty_participates_in (facid DECIMAL, actid DECIMAL)
CREATE TABLE faculty (facid DECIMAL, lname TEXT, fname TEXT, rank TEXT, sex TEXT, phone DECIMAL, room TEXT, building TEXT)
CREATE TABLE participates_in (stuid DECIMAL, actid DECIMAL)
CREATE TABLE student (stuid DECIMAL, lname TEXT, fname TEXT, age DECIMAL, sex TEXT, major DECIMAL, advisor DECIMAL, city_code TEXT)

Which students participate in both Canoeing and Kayaking as their activities? Tell me their student ids.
SELECT T1.stuid FROM participates_in AS T1 JOIN activity AS T2 ON T2.actid = T2.actid WHERE T2.activity_name = 'Canoeing' INTERSECT SELECT T1.stuid FROM participates_in AS T1 JOIN activity AS T2 ON T2.actid = T2.actid WHERE T2.activity_name = 'Kayaking'
SELECT "T1"."stuid" FROM "participates_in" AS "T1" JOIN "activity" AS "T2" ON "T2"."actid" = "T2"."actid" AND "T2"."activity_name" = 'Canoeing' INTERSECT SELECT "T1"."stuid" FROM "participates_in" AS "T1" JOIN "activity" AS "T2" ON "T2"."actid" = "T2"."actid" AND "T2"."activity_name" = 'Kayaking'