Table schema:
CREATE TABLE table_name_18 (horizontal_bar VARCHAR, parallel_bars VARCHAR, pommel_horse VARCHAR, position VARCHAR)

Question: What is the horizontal bar score with a pommel horse of n/a, and the position is less than 27, and the parallel bars score is 15.800?
SQL: SELECT horizontal_bar FROM table_name_18 WHERE pommel_horse = "n/a" AND position < 27 AND parallel_bars = "15.800"