CREATE TABLE table_name_78 (pick VARCHAR(255), position VARCHAR(255), nationality VARCHAR(255), college_high_school_club VARCHAR(255))
What was the pick number for the person from the United States who as drafted to the SF position from North Carolina?
    
SQL: SELECT pick FROM table_name_78 WHERE nationality = "united states" AND college_high_school_club = "north carolina" AND position = "sf"