from decimal import Decimal, getcontext
getcontext().prec = 100
N = Decimal(input())

if N==0 :
	print(4)
else:
	x = Decimal(4.0)
	y = Decimal(3.0)
	while N != 1:
		x = y*Decimal(19) - x*Decimal(12)
		x /= Decimal(4.0)
		x,y = y,x
		N = N - 1
	print(y)