Hill encryption (devised by mathematician Lester S.\ Hill in 1929) is a technique that makes use of matrices and modular arithmetic. It is ideally used with an alphabet that has a prime number of characters, so we'll use the $37$ character alphabet $ A, B, \ldots, Z, 0, 1, \ldots, 9,$ and the space character. The steps involved are the following:
Replace each character in the initial text (the plaintext) with the substitution $A \rightarrow 0, B\rightarrow 1, \ldots, (space) \rightarrow 36$. If the plaintext is ATTACK AT DAWN this becomes
$$0\ 19\ 19\ 0\ 2\ 10\ 36\ 0\ 19\ 36\ 3\ 0\ 22\ 13$$
Group these number into three-component vectors, padding with spaces at the end if necessary. After this step we have
$$
\left(
\begin{array}{c}
0 \\ 19 \\ 19
\end{array}
\right)
\left(
\begin{array}{c}
0 \\ 2 \\ 10
\end{array}
\right)
\left(
\begin{array}{c}
36 \\ 0 \\ 19
\end{array}
\right)
\left(
\begin{array}{c}
36 \\ 3 \\ 0
\end{array}
\right)
\left(
\begin{array}{c}
22 \\ 13 \\ 36
\end{array}
\right)
$$
Multiply each of these vectors by a predetermined $3 \times 3$ encryption matrix using modulo $37$ arithmetic. If the encryption matrix is
$$
\left(
\begin{array}{ccc}
30 & 1 & 9 \\
4 & 23 & 7 \\
5 & 9 & 13
\end{array}
\right)
$$
then the first vector is transformed as follows:
$$
\begin{eqnarray*}
\left(
\begin{array}{ccc}
30 & 1 & 9 \\
4 & 23 & 7 \\
5 & 9 & 13
\end{array}
\right)
\left(
\begin{array}{c}
0 \\ 19 \\ 19
\end{array}
\right)
& = &
\left(
\begin{array}{c}
%(30(0) + 1(19) + 9(19)) \mod 37 \\
%(4(0) + 23(19) + 7(19)) \mod 37 \\
%(5(0) + 9(19) + 13(19)) \mod 37
(30 \times 0 + 1 \times 19 + 9 \times 19) \mod 37 \\
(4 \times 0 + 23 \times 19 + 7 \times 19) \mod 37 \\
(5 \times 0 + 9 \times 19 + 13 \times 19) \mod 37
\end{array}
\right) \\
& = &
\left(
\begin{array}{c}
5 \\ 15 \\ 11
\end{array}
\right)
\end{eqnarray*}
$$
After multiplying all the vectors by the encryption matrix, convert the resulting values back to the $37$-character alphabet and concatenate the results to obtain the encrypted ciphertext. In our example the ciphertext is FPLSFA4SUK2W9K3.
This method can be generalized to work with any $n \times n$ encryption matrix in which case the initial plaintext is broken up into vectors of length $n$. For this problem you will be given an encryption matrix and a plaintext and must compute the corresponding ciphertext.
Input begins with a line containing a positive integer $n \leq 10$ indicating the size of the matrix and the vectors to use in the encryption. After this are $n$ lines each containing $n$ non-negative integers specifying the encryption matrix. After this is a single line containing the plaintext consisting only of characters in the $37$-character alphabet specified above.
Output the corresponding ciphertext on a single line.
3 30 1 9 4 23 7 5 9 13 ATTACK AT DAWN
\n · · \n · · \n · · \n · · \n
FPLSFA4SUK2W9K3
\n
6 26 11 23 14 13 16 6 7 32 4 29 29 26 19 30 10 30 11 6 28 23 5 24 23 6 24 1 27 24 20 13 9 32 18 20 18 MY HOVERCRAFT IS FULL OF EELS
\n · · · · · \n · · · · · \n · · · · · \n · · · · · \n · · · · · \n · · · · · \n · · · · · \n
W4QVBO0NJG5 Y76H5A6XHR11BV670Z
· \n