typedef long long ll;
const ll N = 100005;
using namespace std;
struct info {
	ll a, b;
} x[N];
bool cmp(const info&A, const info&B) {
	return A.a < B.a;
}
ll n, ans, s[N];
int main() {
	freopen("mm.in", "r", stdin);
	freopen("mm.out", "w", stdout);
	cin >> n;
	for (int i = 1; i <= n; i++)cin >> x[i].a >> x[i].b;
	sort(x + 1, x + n + 1, cmp);
	for (int i = 1; i <= n; i++)s[i] = s[i - 1] + x[i].b;
	for (int i = 1; i <= n; i++)for (int j = i; j <= n; j++)ans = max(ans, s[j] - s[i - 1] - x[j].a + x[i].a);
	printf("%lld", ans);
	return 0;
}

还是站外题……

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