use strict;

my $vowels="aeiou";

for my $str (qw(abcdefghijklmnopqrstuvwxyz missing_vowels)) {
  my $tmp_v = $vowels;
  LOOP: {
    if ($str =~ /\G[^$tmp_v]*([$tmp_v])/i) {
      $tmp_v =~ s/$1//i;
      print "Succeeded: $str\n" and last LOOP unless $tmp_v;
      redo LOOP;
    }
    print "Failed: $str\n" and last LOOP;
  }
}