func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MAXN = 3e5 + 10;   long long n, a, d[MAXN], v[MAXN], P[MAXN];   vector<pair<int, long long> > vc;   long long ans;   int main() {     cin >> n >> a;     vc.push_back({0, 0});     P[0] = -1e18;     for (int i = 0; i < n; i++) {       cin >> d[i] >> v[i];       ans = max(ans, a - v[i]);       v[i] -= a;       if (i == 0) continue;       v[i] += v[i - 1];       long long mn;       if (i >= 2)         mn = v[i - 2];       else         mn = 0;       while (!vc.empty() && vc.back().first <= d[i] - d[i - 1])         mn = max(mn, vc.back().second), vc.pop_back();       vc.push_back({d[i] - d[i - 1], mn});       mn -= (d[i] - d[i - 1]) * (d[i] - d[i - 1]);       P[vc.size()] = max(P[vc.size() - 1], mn);       ans = max(ans, -v[i] + P[vc.size()]);     }     cout << ans;   }   