$ javac -version
javac 11.0.7
$ java -version
openjdk version "11.0.7" 2020-04-14
OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.7+10)
OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.7+10, mixed mode)

$ java-introcs ABPerms 4 2 2 -V
badc
bdac
cadb
cdab
4
$ java-introcs ABPerms 5 2 2 -V
0
$ ABPerms 6 2 3 -v
cbafed
cbfead
cbfaed
cfbead
cfbaed
dbafec
dbfaec
dbfeac
dcafeb
dcfaeb
dcfeab
dfcaeb
dfceab
dfbaec
dfbeac
ebafdc
ebfdac
ebfadc
ecafdb
ecfdab
ecfadb
efcdab
efcadb
efbdac
efbadc
$ java-introcs ABPerms 7 2 3
0
$ java-introcs ABPerms 7 3 3
882
$ time java-introcs ABPerms 8 3 3
1764

real	0m0.160s
user	0m0.155s
sys	0m0.038s
$ time java-introcs ABPerms 9 3 3
1764

real	0m0.164s
user	0m0.161s
sys	0m0.037s
$ time java-introcs ABPerms 10 3 3
0

real	0m0.143s
user	0m0.121s
sys	0m0.034s
$ time java-introcs ABPerms 10 3 4
107604

real	0m0.234s
user	0m0.234s
sys	0m0.035s
$ time java-introcs ABPerms 11 3 4
213444

real	0m0.627s
user	0m0.633s
sys	0m0.045s
$ time java-introcs ABPerms 12 3 4
213444

real	0m2.235s
user	0m2.250s
sys	0m0.040s
$ time java-introcs ABPerms 13 3 4
0

real	0m0.150s
user	0m0.126s
sys	0m0.034s
$ java-introcs ABPerms 12 3 4 -v | sort | md5
da2086141e3bbd2525c722b4e65fe2f9
$ time java-introcs ABPerms 11 4 4
5323032

real	0m1.826s
user	0m1.824s
sys	0m0.043s
$ time java-introcs ABPerms 12 4 4
25038288

real	0m12.944s
user	0m12.910s
sys	0m0.081s
$ time java-introcs ABPerms 13 4 4
97173648

real	1m35.591s
user	1m35.440s
sys	0m0.187s
$ java-introcs ABPerms 12 4 4 | sort | md5
001c2b83ca9bbe774b2c47385f4d25a6