N=int(input())

prev_ken0=0
ken0=0
prev_ken1=1
ken1=1
prev_ken2=0
ken2=0
for i in range(N-1):
    ken0 = prev_ken2+prev_ken1
    ken1 = prev_ken0
    ken2 = prev_ken1

    prev_ken0=ken0
    prev_ken1=ken1
    prev_ken2=ken2

print( (ken0+ken1+ken2)%(10**9+7) )