Crunch vowels out of a string
Perl, 48 45 43 bytes

Includes +4 for -Xlpi (-X can be left out but leaves ugly warnings on STDERR)

Run with the number after the -i option and the input on STDIN (supports multiple lines too). e.g. perl -Xlpi50 crunch.pl &lt;&lt;&lt; "Duis commodo scelerisque ex, ac consectetur metus rhoncus."

crunch.pl:

s/.*\K[aeiou]|.*\K |.$// while pos=-$^I