Solve 10 1d problems
500 XP
Solve 10 1d problems.
3/10
Uncommon
Recently completed by
Xavier Richard 2k, 
Евгений Авилов 5k, 
Jan šebela 2d, 
MrQuerder [Никита] 3k, 
Алексей Пирожков 4k
and 687 others.
