n = int(input())

a, b, c = 1, 0, 0
ta, tb, tc = 0, 0, 0
mod = pow(10, 9) + 7

while n > 0:
    ta, tb, tc = a, b, c
    a = (tb + tc) % mod
    b = ta
    c = tb
    n -= 1

print(((a + b) % mod + c) % mod)