#include <bits/stdc++.h>
#define ll long long
#define ar array
#define db double
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define rint(l, r) uniform_int_distribution<int>(l, r)(rng)
template<typename T> bool ckmin(T &a, const T &b) { return a > b ? a = b, 1 : 0; }
template<typename T> bool ckmax(T &a, const T &b) { return a < b ? a = b, 1 : 0; }
void test_case() {
int n; cin >> n;
vector<ll> a(n), b(n);
for (int i = 0; i < n; i++) cin >> a[i] >> b[i];
vector<int> idx(n);
iota(all(idx), 0);
sort(all(idx), [&](int x, int y) { return a[x] < a[y]; });
for (int i = 1; i < n; i++) b[idx[i]] += b[idx[i-1]];
vector<ll> mx(n);
ll ans = 0, bst = -1e18;
for (int i = 0; i < n; i++) {
ckmax(bst, a[idx[i]] - (i ? b[idx[i-1]] : 0));
ckmax(ans, -a[idx[i]] + b[idx[i]] + bst);
}
cout << ans << '\n';
}
int main() {
cin.tie(0)->sync_with_stdio(0);
int t = 1;
// cin >> t;
while (t--) test_case();
}
