#!/usr/bin/python

n = raw_input('n = ')

n = int(n)

if n % 3 == 1:
	print "f(n) = %d" % (3**(n//3-1) * 2**2)
elif n % 3 == 2:
	print "f(n) = %d" % (3**(n//3) * 2)
else:
	print "f(n) = %d" % (3**(n//3))