import operator as op
from functools import reduce

def ncr(n, r):
    r = min(r, n-r)
    if r == 0: return 1
    numer = reduce(op.mul, range(n, n-r, -1))
    denom = reduce(op.mul, range(1, r+1))
    return numer//denom


n = int(input())

print(len(list(filter (lambda n:n%2 ==0, [ncr(n,i) for i in range(1,n)]))) )