I think there is a bug. You sort lexically, not numerically. Try this instead:

@values = sort { $a <=> $b } @values;
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Tip #1 from the Basic debugging checklist: use strict and warnings. strict generates a compile error, and warnings generates these (and more):

Scalar value @values[-1] better written as $values[-1] 
Name "main::file" used only once: possible typo
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