f = int(input())
k = 1
p = 1
pp = 0
if f == 1:
    print(1)
elif f == 2:
    print(2)
else:
    f -= 2
    for i in range(f):
        temp = k
        k = p + pp
        pp = p
        p = temp
    print((p + k) % 1000000007)