import numpy as np

def det(a):
    if len(a) == 1:
        return a[0][0]
    if len(a) == 2:
        return a[0][0] * a[1][1] - a[0][1] * a[1][0]

    result = 0
    for col in range(len(a)):
        minor = [
            [a[row][c] for c in range(len(a)) if c != col]
            for row in range(1, len(a))
        ]
        result += ((-1) ** col) * a[0][col] * det(np.array(minor))

    return result

        __
        __