my @x = @{$xy->[0]};
my @y = @{$xy->[1]};
my $i = 0;
my %xyhash;
foreach ( @x ) {
   $xyhash{ $_ } = $y[$i];
    $i++
}
my @x_sorted_by_y = sort{ $xyhash{$b} <=> $xyhash{$a} } keys %xyhash;
my @sorted_y = sort{ $b <=> $a } @y;
print "value of x with largest y = $x_sorted_by_y[0]\n";
print "largest y = $sorted_y[0] \n";