+

+ is HQ9+ with two differences: there are no "H", "Q", or "9" instructions, and all characters that are not + are explicitly ignored.

There is an interpreter written for + in perl in 60 bytes: my$r=$ARGV[0];open my$z,'<',$r or die$!;my$c==<$z>=~/\+/g; There is another interpreter written for + in Lua, Hosted here