func_code_string: #include <bits/stdc++.h>   using namespace std;   unordered_map<char, long long> store;   class thisway {    public:     bool operator()(const char& a, const char& b) {       if (store[a] > store[b]) return true;       return false;     }   };   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     long long n, k;     cin >> n >> k;     string s;     cin >> s;     for (long long i = 0; i < n; i++) {       store[s[i]]++;     }     multiset<char, thisway> ss;     for (auto x : store) ss.insert(x.first);     long long sum = 0;     while (!ss.empty() && k > 0) {       long long pp = store[*(ss.begin())];       ss.erase(ss.begin());       long long req = min(k, pp);       sum += req * req;       pp -= req;       k -= req;       if (pp == 0) store.erase(pp);     }     cout << sum <<   n ;     return 0;   }   