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The universe is at war again because of the Alien oppressive ruler Hitla

Nagasaki. Hitla is so brutal that it throws all beings of a race into black hole

after conquest against one. Now the evil has its mind set to conquest

mother Earth!

As Hitla’s race is far superior in technology, head to head survival chance of

mankind is negligible. So we need to know the exact positions of alien

armies. For that we need to intercept and interpret their messages. As

aliens are very cunning, they have their messages highly encrypted and use

a key buried as substring inside the message to decrypt it. Recent

intelligence report confirms that the key is the biggest prime number and if

a number does not contain any key then this message is just some junk to

confuse the enemies. Now mankind needs a great programmer to crack

these problem.

Unfortunately Hitla has assassinated all programmers but you

due to the fear of cracking messages. Now the fate of mankind depends on

you Sweety.

First line of input contains an integer T denoting the number of test cases

followed by T lines. Each line contains an integer N and a string S denoting

the length of the message and the message.

For each case output must be of the following format Case

X: Y where X is the number of test case starting from 1

and Y is the biggest prime number if there is any.

Otherwise Y will be a string stating This is a junk!.

Constraints

T ≤ 100

0 < N ≤ 10000

Biggest prime number < 10000

Input | Output |
---|---|

4 9 123456789 6 890097 10 4444466666 10 2356122351 | Case 1: 4567 Case 2: 97 Case 3: This is a junk! Case 4: 2351 |

Substring of "123" are "", "1","2", "3", "12", "23", "123"

Explanation:

In first case, substrings which are prime and less than

10000 are 2, 23, 3, 4567, 5, 67, 7, 89. Among which 4567

is the biggest.

In second case, substrings which are prime and less

than 10000 are 89 and 97. Among which 97 is the

biggest.

In third case, there is no substring which is prime.

88% Solution Ratio

rayhan50001Earliest,

Rawaha0909Fastest, 0.0s

rayhan50001Lightest, 131 kB

samhenry97Shortest, 465B

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