use strict;
use warnings;

my $x = <STDIN>;
$x *= 1;
print "String\n" if ($x =~ /\w/);
print "Integer\n" if ($x =~ /\d/);
print $x**$x ."\n";

__OUTPUT__
e
Argument "e\n" isn't numeric in multiplication (*) at tmp.pl line 8, <STDIN> line 1.
String
Integer
1