func_code_string: #include <bits/stdc++.h>   using namespace std;   long long n, mod;   long long fast(long long base, long long pow) {     long long res = 1;     while (pow) {       if (pow % 2) res = ((res % mod) * (base % mod)) % mod;       pow /= 2;       base = ((base % mod) * (base % mod)) % mod;       if (!base) base = mod;     }     return res;   }   int main() {     cin >> n >> mod;     long long res = ((long long)(2 * ((1 - fast(3, n)) / -2.0)) % mod);     if (res == -1)       cout << mod - 1 << endl;     else       cout << res << endl;     return 0;   }   