Group 'host port status' lines, print 'host: p1,p2' for hosts with at least one open port.
Each input line is `host port status` (status = `open` or `closed`).
Group by host. For each host that has at LEAST one open port, print one line:
```
<host>: <port1>,<port2>,...
```
The port list must be ascending numeric. The host order must be lexicographic ascending. Skip hosts with zero open ports entirely.
Sign in to save your code and track progress across devices.
