> .. <span class="hljs-number">19</span>] &amp; <span class="hljs-string">&quot;...&quot;</span> &amp; s[^<span class="hljs-number">20</span> .. ^<span class="hljs-number">1</span>]
  <span class="hljs-keyword">echo</span> s.len, <span class="hljs-string">&quot; digits&quot;</span>

nbText <span class="hljs-string">&quot;&quot;&quot;
### Combinations and permutations
Solution for [Combinations_and_permutations](http://rosettacode.org/wiki/Combinations_and_permutations)&quot;&quot;&quot;</span>

nbCode:
  <s