import sys

sys.setrecursionlimit(10**7)
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LI2(): return list(map(int,sys.stdin.readline().rstrip()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())
def LS2(): return list(sys.stdin.readline().rstrip())


N = I()
mod = 10**9+7

dp1 = [0]*(N+1)  # dp1[i] = i段の登り方の方法の数(最後が1段)
dp2 = [0]*(N+1)  # dp2[i] = i段の登り方の方法の数(最後が2段)
dp3 = [0]*(N+1)  # dp3[i] = i段の登り方の方法の数(最後が3段)

if N == 1 or N == 2:
    print(1)
    exit()

dp1[1] = 1
dp2[2] = 1
dp1[3] = 1
dp2[3] = 1
dp3[3] = 1

for i in range(4,N+1):
    dp1[i] = dp2[i-1]+dp3[i-1]
    dp2[i] = dp1[i-2]+dp3[i-2]
    dp3[i] = dp1[i-3]+dp2[i-3]
    dp1[i] %= mod
    dp2[i] %= mod
    dp3[i] %= mod

print((dp1[-1]+dp2[-1]+dp3[-1]) % mod)