# your code goes here
def f(s):
if (s == 1):
return 1
elif (s == 2):
return 1
elif (s == 3):
return 1
else:
return f(s - 2) + f(s - 3)
n = int(input())
print(f(n))
IyB5b3VyIGNvZGUgZ29lcyBoZXJlCmRlZiBmKHMpOgogICAgaWYgKHMgPT0gMSk6CiAgICAgICAgcmV0dXJuIDEKICAgIGVsaWYgKHMgPT0gMik6CiAgICAgICAgcmV0dXJuIDEgCiAgICBlbGlmIChzID09IDMpOgogICAgICAgIHJldHVybiAxCiAgICBlbHNlOgogICAgICAgIHJldHVybiBmKHMgLSAyKSArIGYocyAtIDMpCgpuID0gaW50KGlucHV0KCkpCnByaW50KGYobikp