def pattern(one, two):
    a = 1
    for i in range(1, one + two + 1):
        a *= i
    for i in range(1, one + 1):
        a //= i
    for i in range(1, two + 1):
        a //= i
    return a

n = int(input())
one, two = 0, 0
ans = 0

if n % 2 == 1:
    one += 1
two = n // 2

for i in range(0, n // 2 + 1):
    ans += pattern(one, two)
    two -= 1
    one += 2

print(ans)