Module: subroutines. recursion


Problem

7 /8


Fast exponentiation

Problem

Raising to a power is faster than n multiplications! To do this, use the following recurrence relations:
\(a^n=(a^2)^{n/2},\ for \ even \ n, \\ a^n=a \cdot a^{n-1 },\ for \ odd \ n.\)

Implement the fast exponentiation algorithm. If you do everything right, then the complexity of your algorithm will be  O(logn) .

Input
The program receives a real number a and an integer n as input. Each number on a separate line.

Imprint 
Output \(a^n\).
 
Examples
# Input Output
1 2
7
128
2 1.00001
100000
2.71827