# 19. [Octave], 144 bytes

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<pre><code>.6;%+-&gt;?|"e"|?&gt;-+%;6.
f=@(x)all(ismember('Hi, Retina!',x))&amp;sum(ismember(x,cat(2,33:36,46,91:93,'')))&lt;6&amp;x(3)&lt;60
%
































</code></pre>

[Try it online!][TIO-jezlhyj2]



**Satisfies:**

1. The first character is a `.`.
2. Its length is an even perfect square.
3. Contains the exact sequence `->`.
4. Contains the exact string `Hi, Retina!`.
5. The second character's Unicode code point, mod 5, is 4.
6. The 10-th character is a `"`, and so is the twelfth character (palindromic rule).
7. The last non-empty line does not have any duplicate characters.
8. The first line is a palindrome of length = 21
9. It contains a `?`.
10. It contains a `|`.
11. It contains a `+`.
12. It is at least 28 lines long.
13. The following characters are used five times in total: `!"#$.[\]`.

**For future answers:**

- The first character is a `.`.
- Its length is an even perfect square.
- Contains the exact sequence `->`.
- Contains the exact string `Hi, Retina!`.
- The second character's Unicode code point, mod 5, is 4, **and** its code point is lower than 60.
- The 10-th character is a `"`, and so is the twelfth character (palindromic rule).
- The last non-empty line does not have any duplicate characters.
- The first line is a palindrome of length = 21
- It contains a `?`.
- It contains a `|`.
- It contains a `+`.
- It is at least 28 lines long.
- The following characters can only be used five times in total: `!"#$.[\]`.
 - Note that four of those are in the first line, due to the palindromic rule, and the exclamation mark is in the `'Hi, Retina!'` string.

[Octave]: https://www.gnu.org/software/octave/
[TIO-jezlhyj2]: https://tio.run/##lVXdbts2FL7PU3BsbJKJzJjyz2KpktOhfwECDOiCAIPjdoxMJUopSpXkzE5dYFdDH6E3e4jd72q53Fv0RTLKovzTZhtG27J4vvMnnY/nJEHBb8T9Pe27jf2WP1xAARdDv7XfcPt0J/SO8IxwKXGUxyK@EBlGLyMLvBJFpPg3yJoR0syn8RqeWQEvsG11Ok6nb3X71oA5g46FECHkcb85wx39195p7PzHuk/fsw/AA@ipFVpHFkPuTvreLiUjRCmhFFmAtS2AKDmOVxtIoUfRuNTtGN0a@vzLb0JUUNdAndEjhMSNUONK3jPytmiDJANpFqkCS6FwpNJpgQnZ26O9BvO8NqkM@sZAfDjnOb39gXWAXr0K/NaA/CKYiPDyKrp@K2OVpO@yvJje/Dyb36IqMx9AH9Zp@uC4DPZEypXEB@zzx4/2xv77aaF1QGcpWgY7rFNv@bfuzMsEn5xESuSYuHPvTARFkkW3Ak@L8PA0OVYF0WV1uZrjy0ykEsOWD8taVpkPjLOW3/5ps9pLkLUNylr@BgiOgYzeCvA8Eyq4As7TZW7AQvDVmZTuhF45XE1Api9JDPQbCENQJEntlNVOWbOJc8@HG651bs1mPhqMPQ8hqJlkbGo2MCnlix/PXkKY3n3asrv7469f6d6fv1evDt19et3eNcY1PZgLXbYiyfkXcd3dN95j3w2uktRd0gHMDw4OAr/XbGaaOFkuakvxbveNa3zX/Do9Pj15BiCHj/QPPDvR@zVtJ7zg9SZyaBhJCeyexax2Lc0dmhc66CWADbs3en2uxiuaFGtsqwxGAYVr/Lu5@BKllzK54BLEPFJGVN46YL2MOJ3mVxLsRtvb3GwD3RlAHnAVGgGfTDR8aIGGyNOHXVQ2RabP1ZZRd8son16AXZuVMj4zsutbMN/2GW76XNYn/Bef13EKVkHnzrar4n@5EsqpK5GJwpS9bh9Mcxwztgch3GMMTxRfE2yLXvo1ax1SqkseX0w4yB04XNU4UiCvuV53GkarpQll7ta@tTt9JvloI8Z4jQ1HLWZ3MV34nAxX8u5gda7rfrUYVh@4D83dQocon3o7eWQNrI5dAptfBOp@Z9zWnanvQsH1gNGHQY8XLqCeL6u2/TWD9ePHaZIVIJ/ntWTdkLVQ83sSKVp2OkxonsqowPBcQUJ8u7/PiDbSrS3Ww6hMzOoyUgZalAtWj9OltslxsMrx6xlYB39oFG7NwgeG4T@MQt3CSt31OKzyaSBrM2O7T3R2eo2Yo6axkDglbiCkDKcKH@GAgFBfLJCS8f3f "Octave – Try It Online"