% slitherlink 173 by Otto Janko, http://www.janko.at/Raetsel/Slitherlink/173.a.htm
slitherlink
hard-
20 15
...2....2.....21.213
212..33....3...22.2.
312..2.2.12.11....1.
......3.3..2.3.302.3
21..3.....322...3.2.
2.......01..32......
212.12.21.....2...13
3.313....1..23...3..
...2...2..32..3.1.2.
.311.3..22......2.1.
2..32.0.233..32.1.3.
...22.22212.2...3..2
.1.0.2....2.3...22.3
.2323...2....2.32.3.
3.3.2...12....2...2.
