#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int ll
using P = pair<int, int>;
#define all(x) x.begin(), x.end()
#define rep(x,s,e) for (auto x=(s)-((s)>(e));x!=(e)-((s)>(e));((s)<(e)?x++:x--))
#define sz(x) (int)x.size()
const char nl = '\n';
const int mod = 998244353;
void solve() {
int n; cin >> n;
vector<P> a(n);
for (auto &i: a)cin >> i.first >> i.second;
sort(all(a));
vector<int> dp(n);
dp[0] = a[0].first+a[0].second;
int res = a[0].second;
rep(i, 1, n) {
res = max(res, dp[i-1]-a[i].first+a[i].second);
dp[i] = max(dp[i-1]+a[i].second, a[i].first+a[i].second);
}
cout << res;
}
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
