func_code_string: #include <bits/stdc++.h>   using namespace std;   int N;   inline bool check(int x) {     long long t = (long long)x * (long long)(x - 1) / 2;     if (x & 1)       t++;     else       t += x / 2;     return t <= N;   }   int main() {     int M;     scanf( %d%d , &N, &M);     vector<int> A;     for (int i = 0; i < M; i++) {       int x;       scanf( %*d%d , &x);       A.push_back(x);     }     sort(A.begin(), A.end(), greater<int>());     int lb = 1, rb = M;     while (lb < rb) {       int mid = (lb + rb + 1) >> 1;       if (check(mid))         lb = mid;       else         rb = mid - 1;     }     long long ans = 0;     for (int i = 0; i < lb; i++) ans += A[i];     printf( %lld n , ans);     return 0;   }   