#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; #define ll long long #define ld long double #define EPS 0.0000000001 #define INF 1e9 #define LINF (ll)INF*INF #define MOD 1000000007 #define rep(i,n) for(int i=0;i<(n);i++) #define loop(i,a,n) for(int i=a;i<(n);i++) #define all(in) in.begin(),in.end() #define shosu(x) fixed< vi; typedef vector vs; typedef pair pii; typedef vector vp; int gcd(int a, int b){ if(b==0) return a; return gcd(b,a%b); } int lcm(int a, int b){ return a/gcd(a,b)*b; } signed main(void) { int n; cin >> n; vector dp(n+1,vi(4)); loop(i,1,min(n,3LL)+1)dp[i][i] = 1; rep(i,n)loop(j,1,4){ loop(k,1,4)if(j != k && i+k <= n)(dp[i+k][k] += dp[i][j]) %= MOD; } int ans = 0; rep(i,4)(ans += dp[n][i]) %= MOD; cout << ans << endl; }