$x=5;
print "In package main \$x: $x\n";

package mypack;
$x=6;
print "In package mypack \$x: $x\n";
print "In package mypack \$main::x: $main::x\n";

package main;
print "In package main \$x: $x\n";
print "In package main \$mypack::x: $mypack::x\n";