A. Repeating Ciphertime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputPolycarp loves ciphers. He has invented his own cipher called repeating.Repeating cipher is used for strings. To encrypt the string s=s_{1}s_{2} \dots s_{m} (1 \le m \le 10), Polycarp uses the following algorithm:  he writes down s_1 ones,  he writes down s_2 twice,  he writes down s_3 three times,  ...  he writes down s_m m times. For example, if s="bab" the process is: "b" \to "baa" \to "baabbb". So the encrypted s="bab" is "baabbb".Given string t — the result of encryption of some string s. Your task is to decrypt it, i. e. find the string s.InputThe first line contains integer n (1 \le n \le 55) — the length of the encrypted string. The second line of the input contains t — the result of encryption of some string s. It contains only lowercase Latin letters. The length of t is exactly n.It is guaranteed that the answer to the test exists.OutputPrint such string s that after encryption it equals t.ExamplesInput
6
baabbb
Output
babInput
10
ooopppssss
Output
oopsInput
1
z
Output
z
6
baabbb

bab
['implementation', '*800']