You are given an array of boolean values, starting with zero or more occurences of False, followed by zero or more occurences of True.

Goal

• Find the first True and return its index
• If there is no True, return -1.

Example

[False, False, False, True, True, True, True] # return 3
[False, False, False, True] # return 3
[False, True] # return 1
[True] # return 0
[] # return -1
[False, False, False, False] # return -1

Note

• The maximum input size is 200000000 for python.
• "A certain module" has been forbidden...