N = int(input())
a = 1
b = 1
c = 0
a_tmp = 0
b_tmp = 0
c_tmp = 0
d = 0
if N == 1:
    print(1)
elif N == 2:
    print(2)
else:
    for i in range(N-2):
        a_tmp,b_tmp,c_tmp = a,b,c
        a = c_tmp % (10**9 + 7)
        b = (a_tmp % (10**9 + 7))+(c_tmp % (10**9 + 7))
        c = (b_tmp % (10**9 + 7))
        d = (a + b + c)%(10**9 + 7)
    print(d)