BIT-WISE
			----------------------

1. To find a number:
11000101 is 2^0+2^2+2^6+2^7 = 197


2. Left shifting:
	0010 1011 << 4  ---> 1011 000


3. Right shifting:
	0010 1011 >> 4	---> 0000 0010
	or it can be filled with the copy of the first bit, instead of 0:
	1011 0010 >> 4  ---> 1111 1011


4. XOR can cancels out:
15 ^ 12 ^ 15 = 12


5. 2^x:
	left-shift 1 by x:
	0000 0001 << x

	so if x = 2, 2^2 = 4 -> 100

	0000 0001 << 2  ---> 0000 0100


6. Is power of 2?
	just do x&(x-1).
	if 0 --> yes!