Simulation of a particular RAM machine model with indirect addressing.

There are 6 available instructions:
add s reg       - append symbol s to register reg
del reg         - delete first symbol from register reg
clr reg         - remove all symbols from register reg
cpy dst src     - copy all symbols from register src to register dst
jmp l           - jump to label lab
jmpif s reg l   - jump to label lab if the first symbol of register reg is s

Any alphanumeric string that appeared in program followed by colon is valid label.

Direct addressing: any alphanumeric string, e.g. `wer32r2r`
Indirect addressing: any address in parentheses, e.g. `(wer32r2r)`

Source is read from stdin.