print "$in wasn't a number!";input() unless $in =~ /\d/;
# is the same as
print "$in wasn't a number!";
input() unless $in =~ /\d/;
# what you want is
print("$in wasn't a number!"),input() unless $in =~ /\d/;

##</code><code>##

print("$in wasn't a number!"),return input() unless $in =~ /\d/;