Simple Encryption

One of the simplest ways to encode a message is a letter shift.

For example, if you shift every letter of the original message by $5$, then A becomes F in the coded message. (B $\to$ G, C $\to$ H, …, T $\to$ Y, U $\to$ Z, V $\to$ A, …, Z $\to$ E) Once you pass the end of the alphabet you wrap back around to A. To decode, simply shift back by the same amount.

A slightly trickier scheme uses a keyword to decide how far to shift. Suppose the keyword is ACT. To encode a message, first remove every non-alphabetic character, then arrange the remaining letters into a block whose width equals the keyword length. For example, take this message:

BANANA & PEEL

Written as a block with the keyword ACT as its header, it looks like this:

Each letter is now shifted, but the shift is not uniform — it depends on the keyword letter at the top of its column. If the column header is A, that column is not shifted; if it is B, the column shifts by $1$; and so on. In this example the third column shifts by $19$, because T is the $20$th letter of the alphabet.

The encoded message is:

Write a program that reads a keyword and a string, then encodes the string. The keyword is never longer than $6$ characters, and the message is always given in uppercase.

The first line contains the keyword. The second line contains the message to encode. The keyword length never exceeds $6$ characters, and the total message length never exceeds $60$ characters.

Output the encoded message on a single line.