$ perl -wle'use strict; my $str2 = "@cce$$ag@!n"; print $str2;'
Global symbol "@cce" requires explicit package name at -e line 1.
Global symbol "$ag" requires explicit package name at -e line 1.
Execution of -e aborted due to compilation errors.

$ perl -wle'use strict; my $str2 = "\@cce\$\$ag\@!n"; print $str2;'
@cce$$ag@!n