func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long mod = 1e9 + 7;   long long dx[] = {-1, 0, 1, 0};   long long dy[] = {0, -1, 0, 1};   int32_t main() {     ios::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     long long n, m;     cin >> n >> m;     vector<pair<long long, long long> > v(m);     for (long long i = 0; i < m; i++) {       cin >> v[i].second >> v[i].first;     }     sort(v.rbegin(), v.rend());     long long ans = v[0].first;     for (long long k = 2; k <= m; k++) {       if (max((k * (k - 1)) / 2 + 1, k * (k / 2)) <= n)         ans += v[k - 1].first;       else         break;     }     cout << ans <<   n ;   }   