Where is the input stored? In @_ I do not think so.

It is stored on the stack, in other words, there is no variable like @_, which you can use

You can however make one

 my @stuff = <STDIN>;
my $thismany = @stuff;
print "I saw this many ", scalar(@stuff), "\n";
print "I saw this many ", int(@stuff), "\n";
print "I saw this many ", 0+@stuff, "\n";
print "I saw this many $thismany\n";
foreach(@stuff){
    print "I saw $_";
}
[download]