#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) { cerr << to_string(h); if(sizeof...(t)) cerr << ", "; DBG(t...); }
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
const int N = 5e5 + 3;
ll a[N], b[N], U[N], pref[N];
void solve() {
int n; cin >> n;
vector<pair<ll, ll>> vec;
for (int i = 1; i <= n; i++) cin >> a[i] >> b[i], vec.push_back({a[i], b[i]});
sort(vec.begin(), vec.end());
ll ans = 0;
for (int i = 1; i < n; i++) {
U[i] = vec[i-1].second - (vec[i].first - vec[i-1].first);
pref[i] = pref[i-1] + U[i];
}
ll mn = 0;
for (int i = 1; i <= n; i++) {
ll S = vec[i-1].second;
//dbg(S, pref[i-1], mn, i);
ans = max(ans, S + pref[i-1] - mn);
mn = min(mn, pref[i]);
}
cout << ans << "\n";
}
signed main() {
ios::sync_with_stdio(false); cin.tie(0);
int t=1; //cin >> t;
while (t--) {
solve();
}
}
/*
3
2 3
4 5
11 2
*/
