N = int(input())
dp_k = [0] * (N + 2)
dp_kk = [0] * (N + 2)
dp_p = [0] * (N + 2)
dp_p[0] = 1

for i in range(1, N + 2):
    dp_k[i] = dp_p[i - 1] % 1000000007
    dp_kk[i] = dp_k[i - 1] % 1000000007
    dp_p[i] = (dp_k[i - 1] + dp_kk[i - 1]) % 1000000007
print((dp_p[N] + dp_k[N] + dp_kk[N]) % 1000000007)