SCHEMA:
CREATE TABLE table_name_67 (year INTEGER, rider VARCHAR, final_position___giro VARCHAR, final_position___tour VARCHAR, final_position___vuelta VARCHAR)
USER:
What is the earliest year of Valdimir Poelnikov, who has a final position-tour bigger than 72, a final position-vuelta less than 77, and a final position-giro less than 57?

QUERY:
SELECT MIN(year) FROM table_name_67 WHERE final_position___tour > 72 AND final_position___vuelta < 77 AND final_position___giro < 57 AND rider = "valdimir poelnikov"