% slitherlink 646 by Otto Janko, http://www.janko.at/Raetsel/Slitherlink/646.a.htm
slitherlink
hard-
17 17
3.3..........3..3
..2.2....1.......
221.2..3.1.1..212
1.1.1.21....312.3
.312.2..2.3.2....
.1......3...3.22.
2..22.12.2.2..3..
2221.3.32.221..1.
31.31....21232.12
..2..2..2....11.3
.22..1.2..2..23..
221..0.21..33...3
3....0.3.1.2.3...
.1.1.3..2.2..3.2.
33....132.2.2.3.3
2.21.3....32.....
...23.1.23...3.20
