"""
This kata is from check py.checkio.org

You are given an array with positive numbers and
a non-negative number N. You should find the N-th
power of the element in the array with the index N.
If N is outside of the array, then return -1. Don't
forget that the first element has the index 0.

Let's look at a few examples:

array = [1, 2, 3, 4] and N = 2, then the result is 3^2 == 9;
array = [1, 2, 3] and N = 3, but N is outside of the array,
so the result is -1.
"""

def index(array, n):
    return array[n] ** n if n in range(len(array)) else -1

print("Tests:")
print(index([1, 2, 3, 4],2))
print(index([1, 3, 10, 100],3))