P = 10 ** 9 + 7

x = 1

y = 0

z = 1

N = int(input()) 

if N == 1:
    
    print(1)
    
    exit()

for i in range(N - 2):
    
    x, y, z = y, z, (x + y) % P
    
print((x + y + z) % P)