func_code_string: #include <bits/stdc++.h>   using namespace std;   void solve() {     int N;     cin >> N;     long long int dp_D = 1, dp = 0, dp_temp;     for (int i = 0; i < N; i++) {       dp_temp = dp_D;       dp_D = 3 * dp;       dp = dp * 2 + dp_temp;       dp %= 1000000007;       dp_D %= 1000000007;     }     cout << dp_D << endl;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     int T = 1;     while (T--) {       solve();     }     return 0;   }   