% slitherlink 172 by Otto Janko, http://www.janko.at/Raetsel/Slitherlink/172.a.htm
slitherlink
hard-
20 15
.3.23.....22....2..3
.....2..112....22.2.
.2.....3.3.223.212.1
3.2..2.3..3.2.132..3
..12231.2...32..31..
....2.23.33....11.3.
3..2.212.2....3.2...
.....2......2.1..3..
221....311..22..1..2
2..22...322222..3.3.
3.2.2.12.......0.23.
..22.2...3.3.2.2..21
...1.113...23..1..2.
.2.322..2.1..12...12
3.32133..1.....13...
