## [Retina](https://github.com/mbuettner/retina), 19 bytes

Byte count assumes ISO 8859-1 encoding.

    O`.+
    Mm1`^(.+)¶\1
    0

The input should be linefeed-separated. Output is `0` for falsy and `1` for truthy.

[Try it online!][1] (Slightly modified to support multiple space-separated test cases instead.)

### Explanation

    O`.+

Sort the lines in the input. If a prefix exists it will end up directly in front of a string which contains it.

    Mm1`^(.+)¶\1

Try to match (`M`) a complete line which is also found at the beginning of the next line. The `m` activates multiline mode such that `^` matches line beginnings and the `1` ensures that we only count at most one match such that the output is `0` or `1`.

    0

To swap `0` and `1` in the result, we count the number of `0`s.


 [1]: http://retina.tryitonline.net/#code=JShgXHMKwrYKT2AuKwpNbTFgXiguKynCtlwxCjA&input=SGVsbG8gV29ybGQKQ29kZSBHb2xmIElzIENvb2wKMSAyIDMgNCA1ClRoaXMgdGVzdCBjYXNlIGlzIHRydWUKMTExIDAxMCAwMDAgMTEwMSAxMDEwIDEwMDAgMDExMSAwMDEwIDEwMTEgMDExMCAxMTAwMSAwMDExMCAxMDAxMSAxMTAwMCAwMDExMSAxMDAxMAo0IDQyCjEgMiAzIDM0ClRoaXMgdGVzdCBjYXNlIGlzIGZhbHNlIHQKSGUgc2FpZCBIZWxsbwowIDAwIDAwMDAxCkR1cGxpY2F0ZSBEdXBsaWNhdGUgS2V5cyBLZXlz