|Author:||I. Tuphanov||Time limit:||1 sec|
|Input file:||input.txt||Memory limit:||256 Mb|
FEFU computer scientists use a duplication method to detect errors in network data transfer. Each bit of data is duplicated. The duplicate follows the original bit. Each byte therefore is transferred as a message of two bytes. The first byte of the message encodes high bits of the original byte, the second byte encodes low bits.
For example, a byte 67 is encoded as follows:
Scientists received two bytes. Now they need to find out what the original byte was.
Input file contains two integers designating two received bytes.
Output file must contain a single integer — the original byte, or −1 if there was an error during transfer.
Both input integers are in the range from 0 to 255.
|No.||Input file (
||Output file (|