# -*- coding: utf-8 -*-
N = input()
mem1 = 1
mem2 = 0
mem3 = 0
for i in xrange(1, N):
    mem1, mem2, mem3 = mem3 % 1000000007, mem1, (mem1 + mem2)
print (mem1 + mem2 + mem3) % 1000000007