# Parity Bit Generator

Elementary+

During the last I3E Industrial Conference in Robo-city, a new version of the communication protocol R2HI 2.0 (Robot-to-Human Interface) was adopted. A new version of the R2HI interface extends the existing one by adding an error detection feature. This feature allows us to send data to robots located a long distance away near some human settlements with higher level of reliability. During the data transmission some bits can be substituted due to external events (radiation impact, different noises etc.). In R2HI 2.0 simple parity bit check technique is proposed.

R2HI 2.0 interface specification:
1. Data packages (message) are represented as a list of int numbers (0 ≤ number ≤ 255):
[d1, d2, d3, ..., dn], where d1 is the first letter in message
2. Each decimal number is an ASCII-code of respective characters in binary + parity bit
Example:

```    Chr | Dec  |   Bin   |P|  Bin + P | Dec
---------------------------------------
'P' |  80  | 1010000 |0| 10100000 | 160
'y' | 121  | 1111001 |1| 11110011 | 243
't' | 116  | 1110100 |0| 11101000 | 232
'h' | 104  | 1101000 |1| 11010001 | 209
'o' | 111  | 1101111 |0| 11011110 | 222
'n' | 110  | 1101110 |1| 11011101 | 221

Message = [160, 243, 232, 209, 222, 221]
```

You have to implement an "R2HI 2.0 translator/analyzer" that translates a received data package (list of int) into a string message. Before the translation, erroneous numbers must be removed from the package (list). Erroneous means the decimal value contains a wrong (odd) number of '1' in a binary form:

'P' → 80 → 1010000 + 0 → 10100000 → ...101 1 0000... → 10110000 (Erroneous, 4-th bit was inverted)
Notice: During the data transmission one bit can be wrong (substituted) at most.

How it Works:
Input message: [144, 16, 210, 214]
Remove erroneous characters (binary): [10010000, 00010000 , 11010010, 11010110 ]
Binary result (remove parity bit): [1001000 0 , 1101001 0 ]
Decimal: [72, 105]
Message string (ASCII): "Hi"

Input: A list of int numbers

Output: Message as a string

Example:

How it is used: Parity bits are used as the simplest form of error detecting code . They allow you to detect odd numbers of bit substitutions in data.

Precondition: 1 ≤ len(message) < 100
all(m for m in message if i.isprintable())
0 ≤ number ≤ 255

17
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