Context: CREATE TABLE table_name_72 (length__m_ INTEGER, country VARCHAR, maximum_grade___percentage_ VARCHAR, vertical_drop__m_ VARCHAR)
Question: What is the shortest length of a track in Norway that has a maximum grade of 15% and a vertical drop less than 122.22 m?
Answer: SELECT MIN(length__m_) FROM table_name_72 WHERE maximum_grade___percentage_ = "15" AND vertical_drop__m_ < 122.22 AND country = "norway"