Mike does not want others to view his messages, so he find a encode method Base64.
Here is an example of the note in Chinese Passport.
The Ministry of Foreign Affairs of the People‘s Republic of China requests all civil and military authorities of foreign countries to allow the bearer of this passport to pass freely and afford assistance in case of need.
When encoded by \texttt{Base64}, it looks as follows
VGhlIE1pbmlzdHJ5IG9mIEZvcmVpZ24gQWZmYWlycyBvZiB0aGUgUGVvcGxlJ3MgUmVwdWJsaWMgb2Yg
Q2hpbmEgcmVxdWVzdHMgYWxsIGNpdmlsIGFuZCBtaWxpdGFyeSBhdXRob3JpdGllcyBvZiBmb3JlaWdu
IGNvdW50cmllcyB0byBhbGxvdyB0aGUgYmVhcmVyIG9mIHRoaXMgcGFzc3BvcnQgdG8gcGFzcyBmcmVl
bHkgYW5kIGFmZm9yZCBhc3Npc3RhbmNlIGluIGNhc2Ugb2YgbmVlZC4=
In the above text, the encoded result of \texttt{The} is \texttt{VGhl}. Encoded in ASCII, the characters \texttt{T}, \texttt{h}, and \texttt{e} are stored as the bytes
84![技术分享]()
,
104![技术分享]()
,
and
101![技术分享]()
,
which are the
8![技术分享]()
-bit
binary values
01010100![技术分享]()
,
01101000![技术分享]()
,
and
01100101![技术分享]()
.
These three values are joined together into a 24-bit string, producing
010101000110100001100101![技术分享]()
.
Groups of
6![技术分享]()
bits (
6![技术分享]()
bits have a maximum of
2
6
=64![技术分享]()
different binary values) are converted into individual numbers from left to right (in this case, there are four numbers in a 24-bit string), which are then converted into their corresponding Base64 encoded characters. The Base64 index table is
0123456789012345678901234567890123456789012345678901234567890123
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/
In the above example, the string
010101000110100001100101![技术分享]()
is divided into four parts
010101![技术分享]()
,
000110![技术分享]()
,
100001![技术分享]()
and
100101![技术分享]()
,
and converted into integers
21,6,33![技术分享]()
and
37![技术分享]()
.
Then we find them in the table, and get V, G, h, l.
When the number of bytes to encode is not divisible by three (that is, if there are only one or two bytes of input for the last 24-bit block), then the following action is performed:
Add extra bytes with value zero so there are three bytes, and perform the conversion to base64. If there was only one significant input byte, only the first two base64 digits are picked (12 bits), and if there were two significant input bytes, the first three
base64 digits are picked (18 bits). ‘=‘ characters are added to make the last block contain four base64 characters.
As a result, when the last group contains one bytes, the four least significant bits of the final 6-bit block are set to zero; and when the last group contains two bytes, the two least significant bits of the final 6-bit block are set to zero.
For example, base64(A) = QQ==, base64(AA) = QUE=.
Now, Mike want you to help him encode a string for
k![技术分享]()
times. Can you help him?
For example, when we encode A for two times, we will get base64(base64(A)) = UVE9PQ==.
The first line contains an integer
T![技术分享]()
(
T≤20![技术分享]()
)
denoting the number of test cases.
In the following
T![技术分享]()
lines, each line contains a case. In each case, there is a number
k(1≤k≤5)![技术分享]()
and a string
s![技术分享]()
.
s![技术分享]()
only contains characters whose ASCII value are from
33![技术分享]()
to
126![技术分享]()
(all
visible characters). The length of
s![技术分享]()
is no larger than
100![技术分享]()
.
For each test case, output Case #t:, to represent this is t-th case. And then output the encoded string.
Case #1: TWlrZQ==
Case #2: Vmtaa2MyTnNjRkpRVkRBOQ==