n = int(raw_input())
l = [[0,0,0] for _ in range(n+1)]
l[0][0] = 1
l[1][0] = 1
l[2][1] = 1
for i in range(3,n+1):
    l[i][0] += (l[i-1][1] + l[i-1][2]) % (10**9+7)
    l[i][1] += (l[i-2][0] + l[i-2][2]) % (10**9+7)
    l[i][2] += (l[i-3][0] + l[i-3][1]) % (10**9+7)
print sum(l[n]) % (10**9+7)