n=int(input())
if n==1:print(1)
elif n==2 or n==3:print(2)
else:
 n-=3
 k=l=m=1
 while n:
  t=k
  k=l+m
  m=l
  l=t
  k%=1000000007
  n-=1
 print((k+kk)%1000000007)