#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define pii pair<int, int>
#define fi first
#define se second
#define __builtin_popcount __builtin_popcountll
#define all(x) (x).begin(), (x).end()
#define debug(a, l, r) for (int i = (l); i <= (r); ++i) cout << (a)[i] << ' '; cout << '\n';
struct Item{
int a, b;
};
const int MAXN = 5e5 + 5;
int n, pref[MAXN]; Item items[MAXN];
void init() {
cin >> n;
for (int i = 1; i <= n; ++i) {
int a, b; cin >> a >> b;
items[i] = {a, b};
}
sort(items + 1, items + n + 1, [] (const Item &i, const Item &j) {
return i.a < j.a;
});
}
void solve() {
for (int i = 1; i <= n; ++i)
pref[i] = pref[i - 1] + items[i].b;
int mi = pref[0] - items[1].a;
int res = -1e18 - 7;
for (int i = 1; i <= n; ++i) {
res = max(res, pref[i] - items[i].a - mi);
mi = min(mi, pref[i] - items[i + 1].a);
}
cout << res;
}
signed main() {
#ifdef NCTHANH
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(0);
cin.tie(nullptr); cout.tie(nullptr);
init();
solve();
return 0;
}
