n=int(input())
ex=[0]*21
def Ex(N):
	if N<1:			return 0
	if ex[N]>0:		return ex[N]
	ex[N]=(Ex(N-1)+Ex(N-2)+Ex(N-3)+Ex(N-4)+Ex(N-5)+Ex(N-6))/6+1
	return ex[N]
print(Ex(n))