func_code_string: #include <bits/stdc++.h>   using namespace std;   template <class T1, class T2>   ostream& operator<<(ostream& os, const pair<T1, T2>& p) {     os <<  {  << p.first <<  ,   << p.second <<  } ;     return os;   }   template <class T>   ostream& operator<<(ostream& os, const vector<T>& p) {     os <<  [ ;     int i = 0;     for (typename vector<T>::const_iterator it = p.begin(); it != p.end(); ++it) {       os << (i == 0 ?    :  ,  ) << *it;       i++;     }     os <<  ] ;     return os;   }   template <class T>   ostream& operator<<(ostream& os, const set<T>& p) {     os <<  [ ;     int i = 0;     for (typename set<T>::const_iterator it = p.begin(); it != p.end(); ++it) {       os << (i == 0 ?    :  ,  ) << *it;       i++;     }     os <<  ] ;     return os;   }   template <class K, class V>   ostream& operator<<(ostream& os, const map<K, V>& p) {     os <<  [ ;     int i = 0;     for (typename map<K, V>::const_iterator it = p.begin(); it != p.end(); ++it) {       os << (i == 0 ?    :  ,  ) << *it;       i++;     }     os <<  ] ;     return os;   }   template <class T>   string toString(const T& o) {     stringstream ss;     ss << o;     string ret;     getline(ss, ret);     return ret;   }   template <class T>   vector<T> subv(const vector<T>& v, int from, int to) {     return vector<T>(v.begin() + min(max(0, from), (int)v.size()),                      v.begin() + min(max(0, to), (int)v.size()));   }   pair<int, int> operator+(const pair<int, int>& a, const pair<int, int>& b) {     return make_pair(a.first + b.first, a.second + b.second);   }   pair<int, int> operator*(const int& a, const pair<int, int>& b) {     return make_pair(a * b.first, a * b.second);   }   int main() {     int n;     cin >> n;     if (n == 1) {       cout <<  a na nb nb n ;     } else if (n == 2) {       cout <<  aa nbb ncc ndd n ;     } else {       if (n % 2 == 0) {         for (int i = 0; i < n / 2; ++i) cout << (i % 2 == 0 ?  aa  :  bb );         cout << endl;         for (int i = 0; i < n / 2; ++i) cout << (i % 2 != 0 ?  aa  :  bb );         cout << endl;         cout <<  e ;         for (int i = 0; i < n / 2 - 1; ++i) cout << (i % 2 == 0 ?  cc  :  dd );         cout <<  e  << endl;         cout <<  e ;         for (int i = 0; i < n / 2 - 1; ++i) cout << (i % 2 != 0 ?  cc  :  dd );         cout <<  e  << endl;       } else {         for (int i = 0; i < n / 2; ++i) cout << (i % 2 == 0 ?  aa  :  bb );         cout <<  e  << endl;         for (int i = 0; i < n / 2; ++i) cout << (i % 2 != 0 ?  aa  :  bb );         cout <<  e  << endl;         cout <<  e ;         for (int i = 0; i < n / 2; ++i) cout << (i % 2 == 0 ?  cc  :  dd );         cout << endl;         cout <<  e ;         for (int i = 0; i < n / 2; ++i) cout << (i % 2 != 0 ?  cc  :  dd );         cout << endl;       }     }     return 0;   }   