A. Cipher Shifertime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputThere is a string a (unknown to you), consisting of lowercase Latin letters, encrypted according to the following rule into string s:  after each character of string a, an arbitrary (possibly zero) number of any lowercase Latin letters, different from the character itself, is added;  after each such addition, the character that we supplemented is added. You are given string s, and you need to output the initial string a. In other words, you need to decrypt string s.Note that each string encrypted in this way is decrypted uniquely.InputThe first line of the input contains a single integer t (1 \le t \le 1000) — the number of test cases.The descriptions of the test cases follow.The first line of each test case contains a single integer n (2 \le n \le 100) — the length of the encrypted message.The second line of each test case contains a string s of length n — the encrypted message obtained from some string a.OutputFor each test case, output the decrypted message a on a separate line.ExampleInput
38abacabac5qzxcq20ccooddeeffoorrcceessOutput
ac
q
codeforces
NoteIn the first encrypted message, the letter a is encrypted as aba, and the letter c is encrypted as cabac.In the second encrypted message, only one letter q is encrypted as qzxcq.In the third encrypted message, zero characters are added to each letter.
38abacabac5qzxcq20ccooddeeffoorrcceess
ac q codeforces 
['implementation', 'strings', 'two pointers', '*800']