Problem Description

Define a mapping from lowercase letters to 8-bit binary strings:

• Convert the ASCII code of a lowercase character to an 8-bit binary number, for example: $a \rightarrow 97 \rightarrow 01100001$.

Now, A has a string $s$ of length $n$ consisting only of lowercase letters. He maps this string to a binary string $t$ of length $8n$.

He shuffles the binary string $t$ to obtain a new binary string $t'$. Please restore the original string $s$ based on the shuffled result.

Input Format

The first line contains an integer $n$.

The second line contains a binary string $t'$ of length $8n$.

Output Format

If there is a solution, output a line containing a string $s$ of length $n$ consisting only of lowercase letters; otherwise, output NIE.

If there are multiple solutions, any valid solution is acceptable.

Sample Input and Output

Sample Input #1

2
1100000011110111

Sample Output #1

ao

Sample Input #2

8
1011111010101100011011011010001010100011111111110001001001011010

Sample Output #2

potyczki

Sample Input #3

1
00011000

Sample Output #3

NIE

Notes

For $100\%$ of the data, $1 \leq n \leq 10^5$.

见题面 Input 部分

见题面 Output 部分