You are given a string, str, as a binary representation of an integer. Your task is to return the number of steps needed to reduce it to $1$ by following these rules:

• If the number is even, divide it by $2$.

• If the number is odd, add $1$ to it.

You can always reach 1 for all provided test cases.

Constraints:

• $1 <=$str.length $<= 500$

• str consists of characters $'0'$ or ...