n=int(input())
if n==1:print(1)
elif n==2 or n==3:print(2)
else:
 k=kk=kkk=1
 for i in range(n-3):
  t=k
  k=kk+kkk
  kkk=kk
  kk=t
 print((k+kk)%1000000007)