Inspired by [this article](http://lab.polygonal.de/?p=81).
Neat tricks for speeding up integer computations.

Note: `cin.sync_with_stdio(false);` disables synchronous IO and gives you a performance boost.
If used, you should only use `cin` for reading input
(don't use both `cin` and `scanf` when sync is disabled, for example)
or you will get unexpected results.

##### Multiply by a power of 2
    x = x << 1; // x = x * 2
    x = x << 6; // x = x * 64

###### Divide by a power of 2
    x = x >> 1; // x = x / 2
    x = x >> 3; // x = x / 8

##### Swap integers without a temporary variable
    a ^= b; // int temp = b
    b ^= a; // b = a
    a ^= b; // a = temp

###### Increment / Decrement (slower but good for obfuscating)
    i = -~i; // i++
    i = ~-i; // i--

##### Sign flipping
    i = ~i + 1; // or
    i = (i ^ -1) + 1; // i = -i

###### Modulo operation if divisor is power of 2
    x = 131 & (4 - 1); // x = 131 % 4

##### Check if an integer is even or odd
    (i & 1) == 0; // (i % 2) == 0
    
###### Equality check
    (a^b) == 0; // a == b

##### Absolute value
    x < 0 ? -x : x; // abs(x)
    (x ^ (x >> 31)) - (x >> 31) // abs(x)

###### Equal sign check (both ints are pos or neg)
    a ^ b >= 0; // a * b > 0

##### Rounding, ceiling, flooring
    (x + 0.5) >> 0; // round(x)
    (x + 1) >> 0; // ceil(x)
    x >> 0; // floor(x)