func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     string s;     cin >> s;     int k;     cin >> k;     map<char, int> dict;     for (int i = 0; i < 27; i++) dict[i +  a ] = 0;     for (int i = 0; i < s.length(); i++) dict[s[i]]++;     map<char, int>::iterator it;     vector<pair<int, char> > letras;     pair<int, char> aux;     int distinto;     for (it = dict.begin(); it != dict.end(); ++it) {       aux = make_pair((*it).second, (*it).first);       if (aux.first != 0) letras.push_back(aux);     }     sort((letras).begin(), (letras).end());     distinto = letras.size();     int l = 0;     int j = 0;     while (true) {       j += letras[l].first;       if (j > k) break;       l++;       if (j == k) break;       if (l == distinto) break;     }     if (l == distinto) {       cout << 0 << endl;       cout << endl;       return 0;     }     bool ltras[28];     memset(ltras, 0, sizeof(ltras));     for (int i = l; i < letras.size(); i++) {       ltras[letras[i].second -  a ] = 1;     }     string res =   ;     for (int i = 0; i < s.length(); i++)       if (ltras[s[i] -  a ]) res += s[i];     cout << distinto - l << endl;     cout << res << endl;     return 0;   }   