What is the voting round with the least number of blank votes that is part in the Governor election in  2014 in Acre?
select ?ent where { ?ent wdt:/instance of/ wd:/voting round/ . ?ent wdt:/number of blank votes/ ?obj . ?ent wdt:/part of/ wd:/2014 Acre gubernatorial election/} ORDER BY ASC(?obj)LIMIT 5 