TL HSGHN L9 2022-2023

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

constexpr int N = 5e5 + 5;
int n, id[N];
ll a[N], b[N], c[N], d[N];

void Read()
{
    cin >> n;
    for (int i = 1; i <= n; ++i)
        cin >> a[id[i] = i] >> b[i];
}

void Solve()
{
    sort(id + 1, id + n + 1, [&](const int &x, const int &y)
         { return a[x] < a[y]; });

    ll ans = 0;

    for (int i = 1; i <= n; ++i)
    {
        c[i] = c[i - 1] + b[id[i]];
        d[i] = max(d[i - 1], a[id[i]] - c[i - 1]);

        ans = max(ans, (c[i] - a[id[i]]) + d[i]);
    }

    cout << ans;
}

int32_t main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    Read();
    Solve();
}