Count the set bits

Problem

A feature-flag service stores its flags in one non-negative integer. Print how many flags are on, which means how many 1 bits the number has.

Example

Input

Output

13 is 1101, which has three 1 bits.

Try the problem first. Open one hint at a time.

Hint 1

Python has a method on integers that counts 1 bits.

Hint 2

Or count the "1" characters in bin(n).

Write your Python code, run it on the examples and submit it to hidden tests.