use strict;
use warnings;

my $string = shift;

my $file = 'electricity.txt';
open my $fh, '<', $file or die $!

my $counter = 0;
while (<$fh>) {
	if (s/\Q$string\E/($string)/g) {
		$counter++;
		print "$counter ";
	}
	print;
}

close $fh;