CSES-1630 Tasks and Deadlines

#include <bits/stdc++.h>
using namespace std;

#define pb push_back
#define fi first
#define se second
#define INF LONG_LONG_MAX/1000
#define WA() cin.tie(0)->sync_with_stdio(0)
#define all(x) (x).begin(), (x).end()
#define int long long
#define PII pair<int, int>

signed main() { WA();
    int n; cin >> n;
    vector<PII> v(n);
    for (auto &i : v) cin >> i.fi >> i.se;
    sort(all(v));
    int now, ans; now = ans = 0;
    for (auto &[dur, dl] : v) {
        now += dur;
        ans += dl-now;
    }
    cout << ans;
}