# Task
 The `hamming distance` between a pair of numbers is the number of binary bits that differ in their binary notation. 
# Example
 For `a = 25, b= 87`, the result should be `4`
```
25: 00011001
87: 01010111
```
The `hamming distance` between these two would be 4 ( the `2nd, 5th, 6th, 7th` bit ).
# Input/Output
 - `[input]` integer `a`
  First Number. `1 <= a <= 2^20`
 - `[input]` integer `b`
  Second Number. `1 <= b <= 2^20`
 - `[output]` an integer
  Hamming Distance
def hamming_distance(a, b):
    return sum(x != y for x, y in zip(format(a, "020b"), format(b, "020b")))
def hamming_distance(a, b):
    return sum(x != y for x, y in zip(format(a, "020b"), format(b, "020b")))