use File::Basename;

my $found;
while( <DATA> ) {
  chomp;
  my $bn = basename($_);
  next unless $bn =~ m/^\d+$/;
  $found = $bn;
}
print $found;

__DATA__
/path/to/one/library
/path/to/another
/path/to/another/01
/path/to/another/s
/path/to/another/02
/path/to/another/w1
/path/to/another/03
/path/to/another/1e
/path/to/another/2014