use Set::Scalar;
print "1..21\n";
my $a = Set::Scalar->new("a".."e");
my $b = Set::Scalar->new("c".."g");
my $d = $a->symmetric_difference($b);
print "not " unless $d eq "(a b f g)";
print "ok 1\n";
print "not " unless $a eq "(a b c d e)";
print "ok 2\n";
print "not " unless $b eq "(c d e f g)";
print "ok 3\n";
my $e = $a % $b;
print "not " unless $e eq "(a b f g)";
print "ok 4\n";
print "not " unless $a eq "(a b c d e)";
print "ok 5\n";
print "not " unless $b eq "(c d e f g)";
print "ok 6\n";
my $f = $b->symmetric_difference($a);
print "not " unless $f eq "(a b f g)";
print "ok 7\n";
print "not " unless $a eq "(a b c d e)";
print "ok 8\n";
print "not " unless $b eq "(c d e f g)";
print "ok 9\n";
my $g = $b % $a;
print "not " unless $g eq "(a b f g)";
print "ok 10\n";
print "not " unless $a eq "(a b c d e)";
print "ok 11\n";
print "not " unless $b eq "(c d e f g)";
print "ok 12\n";
my $h = $a % "x";
print "not " unless $h eq "(a b c d e x)";
print "ok 13\n";
print "not " unless $a eq "(a b c d e)";
print "ok 14\n";
my $i = "y" % $a;
print "not " unless $i eq "(a b c d e y)";
print "ok 15\n";
print "not " unless $a eq "(a b c d e)";
print "ok 16\n";
my $j = $a % "c";
print "not " unless $j eq "(a b d e)";
print "ok 17\n";
print "not " unless $a eq "(a b c d e)";
print "ok 18\n";
my $k = "e" % $a;
print "not " unless $k eq "(a b c d)";
print "ok 19\n";
print "not " unless $a eq "(a b c d e)";
print "ok 20\n";
my $l = Set::Scalar->new("a", "b");
my $m = Set::Scalar->new("b", "c");
print "not " unless $l % $m eq "(a c)";
print "ok 21\n";