func_code_string: #include <bits/stdc++.h>   using namespace std;   int toInt(string s) {     int r = 0;     istringstream sin(s);     sin >> r;     return r;   }   long long toInt64(string s) {     long long r = 0;     istringstream sin(s);     sin >> r;     return r;   }   double toDouble(string s) {     double r = 0;     istringstream sin(s);     sin >> r;     return r;   }   string toString(long long n) {     string s, s1;     while (n / 10 > 0) {       s += (char)((n % 10) + 48);       n /= 10;     }     s += (char)((n % 10) + 48);     n /= 10;     s1 = s;     for (long long i = 0; i < s.length(); i++) s1[(s.length() - 1) - i] = s[i];     return s1;   }   bool isUpperCase(char c) { return c >=  A  && c <=  Z ; }   bool isLowerCase(char c) { return c >=  a  && c <=  z ; }   bool isLetter(char c) { return c >=  A  && c <=  Z  || c >=  a  && c <=  z ; }   bool isDigit(char c) { return c >=  0  && c <=  9 ; }   char toLowerCase(char c) { return (isUpperCase(c)) ? (c + 32) : c; }   char toUpperCase(char c) { return (isLowerCase(c)) ? (c - 32) : c; }   int main() {     ios::sync_with_stdio(0);     int n;     cin >> n;     long long count = 1;     int a = 12;     for (long long i = 0; i < n - 1; i++) {       count += a;       a += 12;     }     cout << count << endl;   }   