// looking to shine brighter in this world...
#define TASK "art"
#ifdef LOCAL
#include "local.h"
#else
#include <bits/stdc++.h>
#define debug(...)
#define DB(...)
#endif
using namespace std;
using ll = long long;
using ld = long double;
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define For(i, l, r) for (int i = (l); i <= (r); ++i)
#define Ford(i, r, l) for (int i = (r); i >= (l); --i)
#define Rep(i, n) For (i, 0, (n) - 1)
#define Repd(i, n) Ford (i, (n) - 1, 0)
#define Fe(...) for (auto __VA_ARGS__)
template <class C> inline int isz(const C& c) { return static_cast<int>(c.size()); }
template <class T> inline bool chmin(T& a, const T& b) { return (a > b) ? a = b, true : false; }
template <class T> inline bool chmax(T& a, const T& b) { return (a < b) ? a = b, true : false; }
const bool __initialization = []() {
cin.tie(nullptr)->sync_with_stdio(false);
if (fopen(TASK".inp", "r")) {
(void)(!freopen(TASK".inp", "r", stdin));
(void)(!freopen(TASK".out", "w", stdout)); }
cout << setprecision(12) << fixed;
return true;
}();
constexpr ld eps = 1e-9;
constexpr int inf = 1e9;
constexpr ll linf = 1e18;
// ================================================================================
constexpr int maxn = 5e5 + 5;
int n;
pair<ll, int> a[maxn];
ll pref[maxn];
signed main() {
cin >> n;
For (i, 1, n) cin >> a[i].first >> a[i].second;
sort(a + 1, a + n + 1);
For (i, 1, n) {
pref[i] = pref[i - 1] + a[i].second;
}
// bi + ... + bj - aj + ai
// pref[j] - pref[i - 1] - aj + ai
// (pref[j] - a[j]) - (pref[i - 1] - ai)
ll ans = -linf, mn = linf;
For (i, 1, n) {
chmin(mn, pref[i - 1] - a[i].first);
chmax(ans, pref[i] - a[i].first - mn);
}
cout << ans << '\n';
return 0;
}
