Today we have an unusual code golf: build a program (using only printable ASCII characters, tabs and newlines) that prints out exactly the characters in the printable ASCII space (characters 32 to 126) that don't appear in your program's source code (in any order, however many times you want).

As usual, the goal is to produce the shortest code to do this.

My (admittedly not very good, but does the job!) entry:

3 22
0 306

It's been a while (and everyone is well-rested after Advent Of Code!) so let's run another round of Code Golf.

Your task is navigating in a grid-like labyrinth in a clockwise spiral pattern. As it traverses the matrix, it collects characters, revealing a secret message.
Your challenge: find the shortest, most elegant code to decode this spiral cipher.
Input:
1. A multidimensional string array with comma separated characters (n x n)
2. Starting coordinates X and Y

Output:
The decoded message as a single string

2 21
0 261