func_code_string: #include <bits/stdc++.h>   using namespace std;   const int INF = 1e9;   const long long LINF = 1e17;   const double DINF = numeric_limits<double>::max();   const int ITER = 300;   const int MOD = 1e9 + 7;   const double EPS = 1e-10;   const int MAXN = 1e5 + 10;   int n, m;   vector<pair<int, int> > v;   void solve() {     cin >> n >> m;     for (int i = 1; i <= m; i++) {       int q, w;       cin >> q >> w;       v.push_back({w, q});     }     sort(v.begin(), v.end());     reverse(v.begin(), v.end());     long long ans = 0;     for (int i = 0; i < v.size(); i++) {       long long cnt = i + 1;       long long need =           (cnt & 1) ? cnt * (cnt - 1) / 2 : cnt * (cnt - 1) / 2 + cnt / 2 - 1;       if (need + 1 <= n) {         ans += v[i].first;       }     }     cout << ans << endl;   }   int main() {     cout << setprecision(12) << fixed;     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     int t = 1;     while (t--) {       solve();     }   }   