What is the covered bridge with the lowest number of spans whose instance of is road bridge?
select ?ent where { ?ent wdt:P31 wd:Q1825472 . ?ent wdt:P1314 ?obj . ?ent wdt:P31 wd:Q537127} ORDER BY ASC(?obj)LIMIT 5 
covered bridge: Q1825472 road bridge: Q537127