// created : 2026/02/13 21:11:22
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define all(v) v.begin(), v.end()
void solve() {
int n; cin >> n;
vector<pair<int, int>> vt;
for(int i = 0; i < n; i++) {
int x, y; cin >> x >> y;
vt.pb({x, y});
}
sort(all(vt));
vector<int> dp(n + 5, 0);
dp[0] = vt[0].second;
for(int i = 1; i < n; i++) {
dp[i] = max(dp[i], vt[i].second);
dp[i] = max(dp[i], dp[i - 1] + vt[i].second - (vt[i].first - vt[i - 1].first));
}
cout << *max_element(all(dp)) << '\n';
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int t = 1;
//cin >> t;
while (t--) {
solve();
}
}
