seriously, 5 bytes

Result [link]

WA

Code [DL]

00000000  32 0c ef bf bd                                    |2....|
00000005

stdin

0101000101000111101101101000001011011100111011000010101100000111101101001101111110011010100011111101

stdout

0101000101000111101101101000001011011100111011000010101100000111101101001101111110011010100011111101
2

stderr

strace