from abc import ABC, abstractclassmethod


class Calculator(ABC):

    @abstractclassmethod
    def compute(self):
        pass

class Factorial( Calculator ):
    def compute(self,n):
        num = 1
        while n >= 1:
            num = num * n
            n = n - 1
        return num




n = float(input("Enter n "))

f = Factorial()

print( "n! =", f.compute( n ) )
print( "n!! =", f.compute( f.compute( n ) ) )