use warnings;
use strict;

my $i = shift;

if ( $i eq 'add' ) {
	my $rtn = add( @ARGV );
	print "The sum is: $rtn";
}
elsif ( $i eq 'multiply' ){
	my $rtn = multiply( @ARGV );
	print "Their product is: $rtn";
}

sub add {
	my $sum = 0;
	foreach ( @_ ) {
		$sum += $_;
	}
	return $sum;
}

sub multiply {
	my $product = 1;
	foreach ( @_ ) {
		$product *= $_;
	}
	return $product;
}