func_code_string: #include <bits/stdc++.h>   using namespace std;   const int INF = 1e9 + 7, mod = 1e9 + 9, pw = 31;   const double eps = 1e-11;   long long binpow(long long a, long long b) {     long long rec = 1;     while (b) {       if (b % 2 == 1) {         rec *= a;         rec %= INF;       }       a *= a;       a %= INF;       b /= 2;     }     return rec;   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(NULL);     int n;     cin >> n;     long long x = binpow(3, n * 3) - binpow(7, n);     if (x < 0) x += INF;     cout << x;     return 0;   }   