func_code_string: #include <bits/stdc++.h>   using namespace std;   void err(istream_iterator<string> it) {}   template <typename T, typename... Args>   void err(istream_iterator<string> it, T a, Args... args) {     cerr << *it <<   =   << a << endl;     err(++it, args...);   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     int n, m, a;     cin >> n >> m;     vector<int> cost(m);     for (int i = 0; i < m; i++) cin >> a >> cost[i];     sort(cost.begin(), cost.end(), greater<int>());     int k = 1;     while (true) {       int nxtk = k + 1;       int need = nxtk * (nxtk - 1) / 2;       if (nxtk % 2 == 0) need += nxtk / 2 - 1;       if (need <= (n - 1) && nxtk <= m)         k = nxtk;       else         break;     }     long long res = 0;     for (int i = 0; i < k; i++) res += cost[i];     cout << res;   }   