mod = 10**9+7

n = int(input())

dp = [[0,0,0] for _ in range(n+1)]

dp[1][1] = 1
for i in range(2,n+1):
    dp[i][0] = dp[i-1][1]%mod
    dp[i][1] = (dp[i-1][2])%mod
    dp[i][2] = (dp[i-1][0] + dp[i-1][1])%mod

#print(dp)
print(sum(dp[n])%mod)