%self     total     self     wait    child    calls   name
 37.90      0.31     0.31     0.00     0.00   182007   Array#join
 35.56      0.81     0.29     0.00     0.52       55   Array#permutation
 13.83      0.21     0.11     0.00     0.10   182007   Set#include?
 12.47      0.10     0.10     0.00     0.00   182007   Hash#include?