N = input()
MOD = 10**9 + 7

ans_ken1 = [0] * (N+3)
ans_ken2 = [0] * (N+3)
ans_pa   = [0] * (N+3)

ans_ken1[1] = 1

ans_ken1[2] = 0
ans_ken2[2] = 1
ans_pa[2]   = 1

for i in xrange(3, N+2):
    ans_ken1[i] = ans_pa[i-1]
    ans_ken2[i] = ans_ken1[i-1]
    ans_pa[i]   = (ans_ken1[i-1] + ans_ken2[i-1]) % MOD

print (ans_ken1[N] + ans_ken2[N] + ans_pa[N]) % MOD