You can only chomp an lvalue (this is the reason for the error that you get). Read

perldoc -f chomp

for an explanation.

Even so, I suspect that

print chomp (my $value = <STDIN>);
[download]

will not give you what you expect... Here it prints '1', not the chomped line from STDIN. Why, you ask? Because chomp returns the number of characters removed from the end of its argument(s). Again, see the documentation.