Easy Math > Number Theory

Tom and Jerry are not just any normal boys like others in their class. They are the best programmers in their class. Today is their birthday. So Mike decided to gift something on their birthday. As they happen to be well known programmers, Mike thought of something innovative. He sent an encrypted message to them in which the instruction for finding the gift has been written. If they desire to get their birthday gift, they have to decode the message given in the message and follow the instructions given in the message. The nature of encryption is described below: Prime numbers the positive integers which are only divisible by 1 and surely, number itself. The first of this kind is 2, then comes 3, 5, 7….. and so on. The ith letter of the original message is represented by a number ai. Let *m* is the nearest prime number less than or equal to *ai*. Now if *m* is the *r* th prime (like 2 is the 1st prime, 3 is the 2nd prime), the decoded letter would be ((*r* modulo 26)+1) th lowercase letter in the alphabet. A ‘0’ represents a space (' ') and '-1' represents a period ('.'). For example, let the encoded message contains three numbers like 12 17 -1. The nearest prime less than or equal to 12 is 11. 11 is the 5th prime. (5 modulo 26)+1=6. The 6th letter is ‘f’. Similarly 17 is the 7th prime and (7 modulo 26)+1=8. So the letter is ‘h’. Therefore, the decoded message for the sequence ‘12 17 -1’ represents “fh.”. You need to decode the message and help them get their birthday gift. Input: ------ The first line of input contains *t*, the number of test cases (1<=*t*<=10). For each of next *t* cases, there is a number *n* (1<=*n*<=100) which is followed by *n* space separated integers ai (-1<=*ai*<10000). Output: ------- Print the decrypted messages in separate lines. Sample Input ------------ 2 18 3324 0 6791 7741 3798 6883 8161 0 1873 3254 6302 373 7688 0 7151 7229 6842 -1 13 8707 7452 19 1224 0 3182 9161 0 8804 4391 5867 5280 -1 Sample Output ------------- a quick brown fox. this is easy.

Mehedi Hasan Muaz