#! /usr/bin/env python


"""
hw 5, tasks 1, 3
"""


from __future__ import  division, print_function


# Task 1


# Task 3
"""
sum((Fi, (i=0, n)) = Fn+2 - 1
1. n = 0. F0 = F0+2 - 1 = F0 + F1 - 1 --> F1 = 1
The first two elements are 1, so all is OK.
2. next step (n = 1). Fn + Fn-1 = Fn+2 - 1 = Fn + Fn+1 - 1 = Fn + Fn + Fn-1 -1 -->
--> 0 = Fn - 1 --> Fn = 1
"""