Ряды Тейлора cos x

x = float(input())

def factorial(x):
    if x == 0:
        return 1
    else:
        return x * factorial(x - 1)

pi = 3.14159265359
x = x - int(x / pi)//2 * 2*pi

cos = 0
if x > pi:
    x -= 2 * pi
for n in range(20):
    cos += ((-1) ** n * x ** (2*n)) / (factorial(2*n))
print(cos)