use strict;
use warnings;

if ($ARGV[0] eq "add") 
     { 
     $rtn = add($ARGV[1]); 
     print "The sum is: $rtn";
     } 
elsif ($ARGV[0] eq "multiply") 
     { 
     $rtn = multiply($ARGV[1]); 
     print "The product is: $rtn";
     } 
else {
     # error message goes here
     # argv[0] was neither add nor multiply
     }

sub add { 
 
}

sub multiply { 
 
}